Uncertain as to how many combinations can do this, I'd imagine slow fall and rocket boots might work also. If you're a warlock this goes well with two stealthers who can creep round to the platform you initially land on and continue with the same guide from there.
Here's the macro you'll be using (Make sure you have flexweave underlay)
Code:
#showtooltip
/cast Rocket Jump
/use 15
Step Number One - Jump to the platform just above the head of my character as pictured in the screenshot and use the above macro. Note you have to be mounted AND jump first before using the macro for it to work.

Step Number Two - My portal is where you'll have landed, climb up on the boner rock and jump down the next section of the ledge that's in front of you. You'll come across

this pillar, hug it's underneath and use the mount through walls glitch. I've found my mammoth works best though my toon is a goblin, so if you manage the jump on another type of race you may not need it.
If you're having trouble with the edge looking like this it's quite simple to time your rocket jump to get around it. If you're not squeamish about the height then it's possible to shimmy around the edge of it.
Step Number Three - You'll come to this place, just walk up the ramp and inside is Beth'tilacs lair. Without doing sod all 
Work In Progress below, give a helping hand if you can figure it out. As soon as you get to the last step of this part of the guide you will get an earthquake and fall through the ground and DIE. You also cannot stand on the firey stones or you will... die.
What's that you say? You're having trouble with the boss and want to use the cheese tactic? Well look no further my friend! Just walk further around the edge until you see

Jump up to the bit on my left and jump towards the head of my portal and you'll land on this

From this bit just jump to where my portal is and you'll be up there in no time!




From here just mount and jump to the red ledge as seen here:

and here my portal is where I was in the last screenshot!

Hope you got familiar with that rocket jump macro, cause again here's where we're aiming (Just above my head)

aaand again macro/normal jump to the platform above my portal

I've tried my own methods, other peoples and outlandish ones and it seems you can't get to that web without standing on that same platform.