How to draw a tiled texture on a post process shader

Hi there. I have messed around with some simple CG shaders before, but I have not done post processing, either in CG or GLSL. This goal I have is a bit above my league, but I hope that with some direction I'll be able to complete it.

My goal is to represent lines in 3d space as squiggly 2d lines on the screen. My idea is to pass endpoints of the lines into the shader and have it draw a tiled sprite over each one.

The two big inhibitors here are that A. I don't know how to pass info into a post-process shader (Is this even possible, given that it's on the camera and not on a material?) and B. I don't know how to draw tiled sprites at arbitrary positions on the screen.

I'd love some help on those questions, and any direction on this is appreciated as well. I do not use stack overflow frequently, so if there is anything I could do to make this more clear, or if I need to separate it into multiple questions, please let me know and I'll be happy to oblige. Thanks.