1. Rent a couple of cores from your favourite cloud provider (linux is usually cheapest).
2. Right now the fastest miner is jhProtominer. Its even much easier to compile and run than a Protoshares client, instructions are in the ypool thread.
3. Compile it on one machine, copy it to the others. Ypool takes quite a large cut (6%!), but his new miner is at least 2x faster than the newest stock client.
Profit margins are shrinking and I'm probably out on the next difficulty change, if the price doesn't move up significantly in the mean time.