One of our members (Rogue) has suggested removing the rear engine lift bracket which will give you more room. Other than that, it'* just a lot of twisting and pulling. They can be a PITA to get off, especially the first time. Be sure to add some dielectric grease when you put the boots back on to make it easier next time.
You may as well just buy a new set of wires and plan on breaking these to get them off. Twisting them helps to break them loose but it gets so hot back there that the wire gets brittle and using the necessary force to get them off often times ends up in breaking them.
Had a similar problem while helping a friend with an Impala, and this was even with the engine rotated forward!
But anyway, we finally got them by putting a small pair of channel locks onto the boots and twisting until the boots broke loose from the plugs, as they were somewhat fused together by the heat, popped right off after that, I would say yours are in a similar condition.
But like Rogue said, just plan on breaking them. It gives you an excuse to buy new ones anyway.