Instructions on how to root it here, on this hideous site
Apparently you can flash the S ROMs to the SL, but do not flash the kernel or you lose the 1.7GHz on the CPU (But I guess with a custom OC kernel you could easily get it back up there)
Looks like these guys should know more too
Off topic, tried the latest ROM build, 4.2.2, for my transformer you recommended. Tried the kernel with it to but the phone kept getting stuck on "starting apps". Fast without the kernel tho and better than AOKP.
Now back on topic...haha