fyi... you don't have to edit the config.wtf file. that field can be set in the maximizer panel for each region.
just set the game resolution to whatever you want (you don't have to select something from the list)

otherwise, a very useful video for people trying to set up keyclone



btw, you can also import your maximizer layout... either from a friend or from the sample set i have on Solid ICE
http://solidice.com/keyclone/layouts/index.html