Last PS3 games I saw with Lan abilities ... were Warhawk and UT3 ...
But yea, this is the most important part.
You need games with LAN-ing abilities
Then from there Just your PS3s, some TVs & a splitter/router with enough ports & the same amount of lan cables as PS3s
Just hook it all up and BAM!
your good to go ...
At the most you might need to set static IPs ...
Maybe ... thats just a side note