Stump does not build with maven. Stump provides no downloadable plugin at this time. I was in contact with the programmer and he told me that he has not much time to support it but he wants to provide a first version "in the next few weeks".
there is another litte plugin "qwickie" hat has currently much less support than Bench/Stump but provides a plugin-update-location for an early version 0.2.2. this version supports clicking onto a wicket:id tag and opening the .java/.html file vice versa. Stefan