Marty, if they are like the MC9, with the rubber gaket and rubber spline, then it's a matter of installing the gasket into the frame, and the windshield into the gasket, and then installing the spline. There's a tool that makes the spline installation eassier. It's a real pain in the butt to install without it. Can be done, but very difficult. You'll want to lube the spline channel with soap to get the spline in the channel.
If it does not fit easily into the frame (and not be too loose), you might need to grind the fiberglass frame to give enough room. If it's too loose, you'll need to fix the frame or the windshield won't stay in.
Have someone to help hold it in place. Suction cups work well for moving the windshields and holding them.
Hope this helps some.
craig