Zip does have a readme, yes. Treat it just like any other weapon mod.
As for the source code modifications, one need only download fs2_open version 3.3 and use it instead of 1.2 (the patched commercial version). If you use the SSLBeam with 1.2, it'll look and work fine. If you run it with 3.3, it'll look fantastic (i.e. with moving textures). Basically requires no special work on your part, just a decision of which version of the exe to double-click on.
What I've done is rename the original exe from FS2.exe to origFS2.exe, and then rename fs2_open_3_3.exe (what you get when you download it from the SCP forum) to FS2.exe. Then it starts from the launcher just like the original did.
SSLBeam stands for Shivan Super Laser Beam.