There's two real ways to do it. Set up bitcoin with a separate wallet on each box and then have your mining client pointing to the localhost and then just transfer the money between the wallets as you find things. Or set up bitcoin in 'server' mode on one box and then point all your miners at that machines IP address.
You need to launch bitcoin.exe with the -server switch if you want to see the bitcoin gui or you can launch bitcoind.exe (in the daemon folder) if you just want it running as a daemon in the background.
There's some settings you need to configure in your bitcoin.conf file as well to allow machines to connect to it.
Check out the second post in this thread
Then just set up your miners to 'solo' mine but point to the servers IP with the ID/Password you added in the bitcoin.conf. If you have any trouble connecting, make sure you opened up the port of any firewalls on the machine you are using as a server.
One caveat. If you do point all your solo boxes at one box and it goes down or the bitcoin client crashes none of your miners will be able to get work and do anything until you get it back up.