ok cool...should be a simple 1 to 1 swap then. You have no idea how many people come in here asking your same question, only to have some big ole GT35 rotated turbo thinking they can just slap it on without any supporting mods.
I've not changed a turbo myself, but I know it's pretty straight forward. The biggest pain is being able to get to all the bolts for the Uppipe and downpipe. Have ratchet extensions available. Obviously you have to pull the TMIC off...and be sure to take it easy on the oil feed line when removing it. I don't believe you have to flush the coolant, but you may have to burp the system since it's been opened up to air.
If you search Google, you'll likely get a how-to from NASIOC. They have tons of useful how-tos, just because its a much bigger site (just full of a lot more jerks )
My first thought was that he'd have to battle the Green Brackets of Death, but not so if he's just swapping in another TD04..whew. Been down that road!
PB Blaster is your friend. A knowledgeable person here (Trainrex) advised me, years ago, to get a can of it, soak the bolts that you'll be working with on the up and downpipes, and then let it sit overnight. Be warned that it smells to high heaven, if you're in a closed garage, as I was. I'm convinced that this was helpful to me, on my 2nd WRX, which had had a few years to gather some rust on the bolts.