First off, get a good map! This is one of the best I've found so far.
The entry to Kael from the Eastern Wastes side is down a long snowy ramp on on the west wall. This ramp has VERY sheer high sides to the north and south and is a 10k damage instant death drop. I don't care if you do have safe fall, IT WON'T SAVE YOU if you go over the edge without some form of levitate up. If you are approaching from the north or south along the zone wall I suggest you slow down once you have walls on your zone wall side and don't run over the top of any more hills without carefully checking if this is the ramp drop. Once you've found the ramp without falling in it, you need to go down it and through the archway, across a huge snowy courtyard to a second archway and in there to the zone tunnel. There are 2 giant guards at the first archway and these can be hard to see because they stand in the corners behind pillars. If you're lucky they won't be there 'cos someone else will have killed them first. I've never seen any other giants between there and the zone.
Before you zone in from Eastern Wastes get a refresh of your SOW if you can. This is an indoor zone and you can't cast SOW inside. When you zone in stay to the right hand wall. There is a giant sentry inside, but he won't agro you from where he is if you stay at the right hand side of the zone entry. From this point on you need either good giant faction or some kind of invis. If you stick to the correct route you won't pass any giants that can see invis, if you stray too far off it you will so try and get it right the first time.
The first bit is easy as there are no turns, just a lot of winding passageway. Go past the sentry and follow round the rock passageway. You'll come to a bit that looks like a sunken paved bridge - go straight across and the winding passage continues to your right on the other side. Follow this round until you come to another paved section with columns on either side. This is your first turn so keep your eyes open. Go about 3/4 of the way down the paved section and you should see a gap between the columns on your right - go through here.
This is the bit marked 'Turn Here' on the picture. If you go straight past it you will end up going down some steps. Use the steps as an indicator that you went wrong and turn back immediately to find the gap, now on your left.
Once you've gone through the gap turn to face your left and this is what you should see. Head straight on into the marked passage way and carry on down the twists and turns.
The passage way will open out to look like the above picture. You want to go almost straight on, using the flag marked here as your signpost. You will drop off a small ledge to reach the flagpole area. Follow down the next bit of winding passage until it opens out again. Here you will be faced with a bit of sunken passageway with higher ledges on each side. Go straight down the middle of the sunken bit and follow the passageway out to the Wakening Lands zone. Congratulations, you made it! Don't get too cocky yet though, you could still run into trouble getting out.
The zone out comes out in the middle of a large wall that has giant sentries spaced all along it. Try and get clear of these before your invis goes down. Personally I recommend running out and turning right to head north up to the zone wall. If you go left and head for the south you're heading down towards the dragon ring where Wuoshi lives. Wuoshi is a big, mean mega agro radius dragon, so if you aren't certain that you have good dragon faction yet I suggest you stay well away from him!
Warning: one of the recent patches made an awkward change to this zone that you need to be wary of. Two named giants that see through invisiblilty have been added in the north east corner of the zone. I'd still recommend using the north wall as your main route across WL (the south wall has lots of little alcove bits that confuse your sense heading and far more nasties), but you now need to be careful to cut out this corner. This is what the corner looks like as you approach it:
The two see invis giants normally stand roughly where the red circle is marked at the top of this last incline. If you follow the red line around the bottom of this and come up to the wall a little further along you should be able to avoid them safely.
Okay, so much for going east to west. Going from west to east should be a simple retracing of steps and it is fairly obvious which way to go except for one part. This is the area where you dropped down the ledge to reach the flagpole and it seems to be causing some people a lot of confusion when going back. I presume this is because you can't climb back UP the ledge to maintain the almost straight line you used to come down.
This is what the area looks like as you approach it going from the Wakening lands side. You want to take a straight line to get into the passageway at the back marked 'C', but the big ledge 'A' gets in the way. Instead you have to go up the stairs marked 'B', go around the ice pillar on your left and then take an immediate right into the passage. I'm assuming this is where people are getting lost because they don't remember going down any stairs on the way through the other way.
This is the way it looks on the map I suggested you go and get. The red line is the route from EW to WL, the blue line is the route back from WL to EW. Going west you ran a straight line and dropped over the middle of the ledge, going east you have to go around the ledge and up the stairs. Whatever you do, DO NOT turn right at the top of the stairs and head south to where the big red 'X' is. There's a bunch of big, mean see invis giants down here that will not only despatch you in short order but will make your CR a nightmare since they will be able to see any invisible character that goes in to try and drag out your corpse.
For going back this way I suggest that small races get a levitate if they can as well as the SOW and invis. There are a few steps you'll have to go up in the passages and as these are giant sized steps they can be a bit of a pain for a small character in a hurry. Anything that speeds up the trip and gets you across before the invis fails is worth having IMHO.
As a final note, it would appear that corpses can not be summoned in Kael from the Wakening Lands zone line but only from the Eastern Wastes side. This is presumably a devious Verant ploy to make you run the zone instead of having only your necro do it and then summon everyone else through using the duel/summon/revive trick. So, if the worst comes to the worst and you have to summon a corpse don't bother getting your necro friend to run through to the west side to save you the run after res - it won't work.