Most people that I've seen doing swaps on Hondas are going from (in most cases) a non-Vtec engine to a Vtec engine....which, although there are ways around it, they usually use a factory Vtec ECU in the harness....which requires at least some mods to the harness itself. So, I guess that it really just depends on what your car currently has....and what you are swapping into it. A great resource is :
http://tech.hybridgarage.com/
I'm sure that someone has already posted this link here somewhere...but here it is again.
-James