The Computer to Computer network obviously does not go through a computer.
However it will still need to use either Ethernet or WiFi to connect to the other computer.
In System Preferences > Network > Advanced Button > TCP/IP tab you should get a Self Assigned IP address.
The computers that join the network should get an IP address in the same range.
My iMac as Network host
I joined my MacBook Pro to this Network and it had an IP that ended .22
I then tested the Bonjour on both and found that the iMac would not open the Buddy list (and therefore never showed up on the iChat 5/Snow Leopard MacBook Pro).
This may be linked to the lack of DNS info.
See this article http://support.apple.com/kb/HT3789
At this point we leave what I know and am confident about.
iMac 2.5Ghz 5i 2011 (Mavericks 10.9)
G4/1GhzDual MDD (Leopard 10.5.8)
MacBookPro 2Gb (Snow Leopard 10.6.8)
Mac OS X (10.6.8),
Couple of iPhones and an iPad
Apple seems to see this problem as a low priority, but it is very frustrating. One of the main reasons I bought a mac was because of the ad hoc network capability and it worked great until OSX Maverick. I called Apple tech support and they just told me to go buy a router, just as if I had a PC. I don't understand why this can't be fixed ASAP. This is the screenshot I read to tech support and they told me they couldn't help: