Get a longer screw that fits the insert and 2nuts. Put the nuts on the screw, screw that assembly into the insert to nearly full depth and tighten the nuts together against the insert so the screw cannot be turned into the insert further. Use the screw to install the insert (may need to add a dab of epoxy or glue if the threads in the ski are damaged). Once installed, hold the screw and back off the jam nuts then remove the screw.
Or, I have recently found inserts that have a small notch in the top that allow you to put them in with a flat head screwdriver.