Alex-
I was in the same boat with corrosion on my '05 4Runner. When I installed my lift, I had no air tools or impact ratchets (or even ratchet wrenches for that matter, they would have sped things up a little bit lol). I soaked all the nuts and bolts in PB Blaster for a couple of days, then used 3' cheater bars to give me some extra leverage where I needed it (mostly on the top nuts on the shocks).
On the rear shocks, I ended up torquing the top nut so hard that it snapped the threaded portion of the shock off completely. On the front shocks, I didn't even bother trying to unbolt the (3) the strut mount bolts on each side. Instead I went with the no-spring compressor method and just removed the top nut (took some extreme leverage) and bottom nut/bolt and slid the shock and spring out the bottom. Not sure if this is possible for installing the DS 2.5/1.5 spacers.
If I hadn't been completely replacing the shocks anyways, I would have been **** outta luck with the broken rear shocks. Anyways, I highly recommend soaking all the bolts in penetrant beforehand and having a spare piece of pipe or whatnot for some extra torque. And plan on breaking stuff in the process lol. Good luck.
/end thread-jack. Sorry to the OP.