I may be in the wrong here, but wouldn't you just put the ip address of the computer that you are running a bitcoin server on as your second machine's host? Then login with the same username and password. You'd have to make sure the firewall ports were open on your local network, but that should work.
Actually here's the thread with the solution:
https://bitcointalksearch.org/topic/how-to-adjust-solo-mining-10266I think what you're looking to do is solo mine with 2 computers from the same bitcoin.exe client, hosted on one computer right?
To do that, set up your bitcoin.exe and guiminer on one computer. In Guiminer set the bitcoin.exe client path on that computer from the "solo utilities." Create the solo username and password (from solo utilities), this will let your other computer connect.
I found this easiest, but on the bitcoin.exe shortcut you use to launch the program, right click and hit properties. in "target" go to the end of the line, add a space, then put
-server
This will make bitcoin.exe start up as a server.
On computer #2, you only need guiminer. Set the server to "solo." For the host, input the ip address of your first computer, if its on a lan, use its 192.168.1.xxx address. Port is 8332, then use the username and password you created on your first computer. Set the device and flags, then hit start mining.
If you cant connect, you might have to go into your router your first computer is on and forward port 8332 to allow connections.
There need to more write to bitcoin.conf
rpcuser=yourusername
rpcpassword=yourpassword
rpcallowip=192.168.1.*
rpcport=8332
And after a quick test on my own network, I can confirm this works...yay, now I have a computer manufactured in 2003 cpu mining for me with an outstanding rate of 1.4 Mhash/s...