If you don't have an LMHosts file already (there is normally a bsaic 'template' file in \winnt\system32\drivers\etc ), just use notepad to create one (remember, you don't want the .txt extension after the file name).
All you need to do then is add the lines:
192.168.0.1 A
192.168.0.2 B
Then save the file. Place a copy of the file on each machine, and away you go.