Sometimes I use a mixture of epoxy, microballoons, and paint (to make the mixture close to the color of the covering). It's a lot less runny than canopy glue, and when you're finished you can add more to seal any gaps. I use No. 1 screws to hold the canopy in place while the glue sets up. For really easy installations, like one I have now where the canopy sits on top of a flat fuselage and has a balsa lip all around the inside, I use WeldBond (available at Ace hardware stores). WeldBond is a lot like canopy glue but I think it's a little bit thicker.