So its been a while since I was in Calculus and I have since forgotten exactly how I would go about doing this. Say I have the X and Y velocities of the player along with the slope of a line. How do I calculate the X and Y velocities after the player collides with the line and then deflects and "bounces" off of the line?

All I can remember is I know I have to get the normal vector of the line but after that I am not sure what to do.

Thanks! :)

That depends on what kind of collision you are looking for. I assume it's an elastic bounce you want, in which case you want to find the reflection vector. It is found using this formula:

v_r = -v_i + 2 * (v_i . n) * n

where v_i is the incoming vector pointing towards the intersection point and n is the surface normal.

Try drawing the model on a piece of paper and you'll see quite easily how this can be deducted.