In a former job, I got to help work with iChat. *shudder*
A) You need an NT server to put it on.
B) You need someone who can read other people's html to make look & feel changes to the html. You need someone who can read lots of pdf manuals and call the iChat guys repeatedly to make the piddling changes (in various and sundry configuration files) your client will want.
Default behavior of iChat is pretty good, but not as good as the demo that your client likely saw. So expect to put in about 3-5 days getting it just right -- after installation, which took maybe 1 day. Our NT guy did that, so I don't know how long it really took.
As for integration with ACS or OpenACS, you may be S.O.L. I know that the custom system we had couldn't be integrated with iChat's notion of users. Possibly if you could get your hands on the source, but all you get is executables and lots of config files.
