Not much, initialize SDL, setup SDL for OpenGL, push the matrix, rotate, scale, transform as normal, pop matrix, flip and proceed as normal.

The problem I found was that you can't combine SDL and OpenGL surfaces successfully on all systems. You can find hacks that work on this, that, or some other thing, but not everything. So up front you have to decide on SDL or OpenGL IMHO.

For this reason I went with pure SDL inside my JumpStart engine, though Project Phoenix uses OpenGL through SDL. You can take a look at that project if you want to see how its done.