I second the last three posts;
Use either paper or film and enlarge on that! You could even save a step and use Harman Direct Positive and enlarge your negative on that. Its not going to be cheap, but youre not "wasting" materials on interpositive.
If you dont wanna buy new things, you just sandwich your negative with another strip of film and expose that to light, to make an interpositive, i cant say for certain how much, so just test. Ortho is good, this way you can do developing by inspection. After that, enlarge your interpositive unto either film or paper and develop accordingly. If using paper, wax/oil it to get it more translucent, and then you're good to go for contact printing. I would use Maco's geniusfilm, but Rolleis lith/graphic films would work as well! Go ortho, and be safe.