I do not understand why you are fighting with an ”ad-hoc” network and “home group” at all.
The problem with SKI and IC Pro must be somewhere else (My guess is that Steinberg has chosen a technical solution that is not good enough on Windows. I.e. the product is not suited to be sold for Windows users)!
I have both OS X Lion and Windows 8 running on the same PC (a “Hackintosh”).
If boot into OS X, IC Pro has no problem at all to connect and control Cubase (note, this computer is connected to the router via Ethernet).
If I boot into Windows 8 (the same computer) It is more or less impossible to connect with IC Pro to Cubase. The same computer, same hardware, same router, same Ethernet, same IP, same network, same Cubase version (7.02), same SKI version etc etc! I have disabled the firewall, changed to WEP, tried both Bonjour via iTunes and the manually installed version but no prevail (except some rare, limited connections).
I think that Steinberg should choose another solution than Bonjour for Windows. It is not fit for the task (and if not, I would like to be refunded. NOT because it is a lot of money but I am tired of being a unpaid (paying) beta tester). 2 working days+ spent on this crappy software.