It's possible, but will require a small bit of python trickery.
You'd need to set some variable equal to len(self.weapons) in def Activate. Then in def Tick, you tell it to spin if that variable == len(self.weapons), and if not, to stop. Like so:
def Activate
self.initWepCount = len(self.weapons)
def Tick
if self.initWepCount == len(self.weapons):
self.Input("Spin", 0, 100)
else:
self.Input("Spin", 0, 0)
Also this needs to be wired with an analog control and you need to set all the weapon ID's on the VS in 'weapons' in Bindings.py.