I'm no expert, been straight shaving less than two weeks. I've been using athletic tape on cardboard. I think you could make paste on paper work. just remember that less is more when it comes to paste. I made that mistake first off, and I found that it actually impeded the paste's cutting ability. you could then finish on clean paper.
Granted I'm sure I can still get my razor sharper with other methods, but it has been very serviceable with the method I'm using.
Straightrazorplace.com has piles of good info in the stickies all over the forum, and the wiki is good too.