Texas Tool Crafters (no affiliation) used to sell a replacement straight-edge S30V blade for the Wave. I have one on my modded Rave and one on my Signal. I don't have a source for these any more, sadly. They do sell replacement blades but not the one I have.

There's a good-sized community of Leatherman modders but very little in the way of parts. I sacrificed a (used from auction site) Rebar to make my Rave. Other brands of multitools may have more parts availability, including some that are designed for user mods.

For tools, the Wave needs two Security Torx size 10 drivers or bits (two because you'll be holding one still while loosening or tightening the other). For a Rebar you need the right pliers for the pivots -- Engineer PZ-58 Screw Pliers are awesome for this, even better than my beloved Knipex Cobra Pliers. Again you'll need two. You will probably also want to consider buying replacement phosphor bronze washers in various sizes.

Once you have the tools all you need is courage. Pictures of each step might also be helpful.

If you want to know everything there is to know about modifying Leatherman tools, metropolicity on EDC Forums is my spirit guide. Metro runs his own business but is very free with his knowledge and expertise.