I'm working on conversion ring to fit it to my astronomy telescope .. it will be something like photon-bazooka .. it has 114mm aperture and 910mm focal distance, just about right for output divergence of this laser without optics.
But other then that, sorry, no ..
Sounds usable to me. Just unscrew original laser lens, and shine it into the telescope (without eye-piece). Try to focus it on wall 10m or further. Focus by moving the laser in and out of the telescope. Generally the crystal should be in the focal point of main mirror/lens.
As for aperture/focal length .. in ideal case, if you shine the laser at distance of focal length, the spot on the wall would be exactly the size of your telescope aperture. If it's more, some of the light will end up on telescope walls, if it's less, not all aperture will be used.
So green lasers generally works well with astronomic telescopes, while direct diode lasers works well with photographic lens.
If you just want nice spot and you don't want to burn at a distance, you can leave the lens on the laser, focus to close, let the beam expand again after focus point .. and then feed that into the telescope. This allows for very good adjustment of the laser output cone. On the other hand, every piece of glass in the system lowers the power.
And also watch for reflections and wear goggles. 400mW is no fun, and telescope is full of shiny surfaces.