Andrew
Couple of points, is your laser a green laser? If it is a plain red one it is no use. Secondly if it is green be aware that they are illegal in most states unless under 1MW, not sure about Canberra.
You can buy lasers with a mounting bracket that replaces your guide scope or drill a couple of holes to mount it to the tube see here
http://www.myastroshop.com.au/produc...p?id=MAS-017H2
Just be aware of the legal situation, I live in the bush so there is almost no air traffic, but wouldn't use one in the city!
Malcolm