Hmmm, I'm trying to find the file atm. I did find the scope_lens.vtf (which appears to be the dirt on your scope) in C:\program files\steam\steamapps\common\counter-strike source\cstrike\materials\overlays
So i guess you can somewhat add a crosshair/lines/ that will appear on your scope, but that will also blur. (Or just make it clear for better sight) =)
Sorry, I am new to this, and having fun just experimenting.