Looks like this guy just did it, so he might be able to give you some info: http://www.son240sx.org/forums/showthread.php?t=31677
Also, this thread might be useful to read through: http://www.son240sx.org/forums/showthread.php?t=8983
IMO, from what I’ve read/seen, an RB20 swap isn’t worth it. If you’re wanting to do a swap, an SR isn’t a bad choice (lots of aftermarket, about as easy as a swap gets), or if you really want to be extreme, throw a V8 into it (again, lots of aftermarket, and you’re getting a good chunk of power off the hop). The RB series usually weighs more than the other options you have, so you’re going to lose some HP-to-HP speed.
Anyways, have at it.