[lug] Mapping a keyboard key to a mouse button

[Ben Burdette]

Does anyone know of a way to do map a keyboard key to a mouse button?  
On windows I've gotten used to using a keyboard key instead of the 
trackball button, because the trackball button feels awkward.  To me its 
more ergonomic to do all the trackball motion with one hand and the 
clicking with the other.  I've explored a few different options in 
ubuntu, but I haven't found anything that obviously has this feature.