I used to do work experience over the summer holidays in a paper mill. (we actually made massive rolls of tisse, but the principles are the same)
For white paper, you need to bleach your pulp (and possibly add a little TiO2 for bright white, or atandard white dyes). For other colours - use dyes.
Making the pulp should be easy - it is then watered right down and passed through mesh untill the appropriate thickness is aquired. For smooth paper - I would assume that you would need a finer particle size in your pulp (filter the diluted pulp?). Hardest part will be getting a smooth even layer on the mesh - practice should get you there. I think some may add a little binder to the pulp/dye/water mix to make the paper stronger.
I think I might try it too sometime.