If it's a vector (made of lines) PDF, you should be able to import into Omega and cut stencils from it.
Just open a blank "page" in Omega. Click File, Import. Find "PDF as vector" in the drop-down menu "Files of Type" and choose that. Then you have to hit OK a couple times, I think.
When the image shows up on the screen, make sure you have it all selected, then click CTRL and 1 together, then click CTRL and 2 together. That process removes the "fill" from the images and makes the lines cuttable.
If it's a raster (made of pixels) PDF, that's a different story. You're going to have to somehow trace or re-draw the image to create lines that can be cut.