Use Rollei Ortho film to contact print

Learnt from friend to use Ortho film to do contact print of BW negative to make BW positive image. Since Ortho film is not-sensitive to red light, the contact print process can be done in the darkroom with red safelight on. Does anyone know about this or process in this way before? Would like to get some insight of this method. And one more thing, during contact print procedure, how to judge the exposure time? Appreciate to get some useful guides on this idea.

For starters, just treat the film as if you were printing on b/w photo paper. Adjust the print exposure/development to get the density/contrast you like. Experimenting with developer types/times/dilutions may be necessary.