I dont think there is magical way to do this (Even in JBoss). The only workaround I found was to explode the ear package, seperately from an ant task, and run an ant task to copy only the war, each time it's changed. Takes about two seconds or less for me. Better than 10 secs!
This is exactly what seam-gen does for you. You just run
ant explodeand it copies the web artifacts and hot deployable classes to JBoss and you can test without the application restarting.
actually after re-reading the documentation i found out it's not possible since it's only hot deploys actions, ejb's and entities will not be hot-deploy (i will have to check that agaiN).