Lots of threads on here (if you haven't already been looking) for a foothold install.Not for everyone but they do come in handy.Googleing it works better than the Search button on here.
1.First thing would be how old is the ski and has it taken on any water.On older skis the answer is probably yes.So you should be prepared to take out the tray and defoam.
@Carrera911 has a build going on right now where he just removed all the foam.Not trying to scare you from doing the holds.Just to expect an issue.
2.You also need to purchase footholds.Couple suggestions would be
@TOBY @tom21 Either one is great to work with.
3.Finally,the glass work.Not hard to do and plenty of YouTube vids on line to help you get started.
4.Materials can be bought at US Compoisites and Soller Composite's (only a suggestion,there are others).
5.Use Epoxy,not vinyl ester from the local auto parts store.lt won't stick to the hull.
Lots more to cover,but this should help you get started.I will add that lifters work pretty good and may be your best bet for now.All depends on how much work you want to do.
And welcome to the X!