What is a standalone m/c?
If it's a regular computer running a windows OS, it's quite straight forward.
Go into the networking control-panel, open the "properties" dialog for your network card. Select TCP/IP and click on properties. Select "Use the following IP adresse" and enter your the desired IP (starting with either 10.0 or 192.168) and use a subnet mask (of for instance 255.255.255.0)
Click ok, and restart computer.
Hope this helps, if not please clarify a bit more what the problem is.