Fitting Polycarbonate or Acrylic Window into Metal Frame

I am replacing my broken garage glass window (single pane) with polycarbonate or acrylic.

I have found many articles on the web covering "How to replace a glass window" but none of them cover the installation of polycarbonate/acrylic glazing.

When I originally removed the glass I noticed that there were no "glazing spring clips". Maybe that is why the window broke so easily.

I need advice regarding the installation of the new polycarbonate/acrylic glazing. I imagine it is:
Step 1: Put some Glazing Silicone Sealant around the inside of the window frame.
Step 2: Lightly push glazing into the sealant and secure in place using spring clips (can I use the same spring clips that you find in greenhouses?).
Step 3: Finally put some more glazing sealant around the outside.

Your feedback is much appreciated.

Numbers 1, 2 and 3 will actually work fine - the only issue I think you'll find is making a nice neat edge with the sealant on the outside of the window. Maybe thats not important? Presumably your old glass was held in with green putty, so common on metal casement windows at one time - the benefit being was that its self curing. Clips weren't used most of the time. Your greenhouse glass clips will work ok so long as the polycarbonate replacement isn't too thick.