One of the most simple ways to do this is to deploy to a myapp.war directory in your deploy dir, instead of actually creating a war file. I usually have two targets in my build script. One which I use 99% of the time which doesn't actually jar / war / war anything, just copies files to directories, and the other which does actually create nice pretty ear / war / jar packages. The really great thing about going with the first option while in development is that ant and maven only copy files which there have been updated copies of. So you can really get the build to test cycle pretty short.
I hope that helps.