You can remove the top of the traceback easily with by raising with the tb_next element of the traceback:
except:
ei = sys.exc_info()
raise ei[0], ei[1], ei[2].tb_next
tb_next is a read_only attribute, so I don’t know of a way to remove stuff from the bottom. You might be able to screw with the properties mechanism to allow access to the property, but I don’t know how to do that.