an aftermarket keyless entry system in a 96 Civic EX? My gf's brother wants me to install one on his Civic. I can't imagine it would be too difficult to do but I thought I'd look into it before I take it on.

I'll be installing a head unit and replacing his front speakers in a few weeks so I'd like to get it done at the same time. Is there anything he'd need to buy besides the keyless entry kit for installation, ie harness or anything?