Running Panda in a child thread is possible, but you'd probably have to compile Panda yourself to support true threading. But you don't need to do this; you can run Panda in the main thread, and coexist happily with pygame--just call taskMgr.step() from time to time instead of calling taskMgr.run().
Still, it seems like a weird thing you're doing, to have two different OpenGL contexts running in the same process. I doubt you'll get very good performance that way (your graphics card will have to switch back and forth between the two different contexts). Whatever problem you're trying to solve, are you sure that's the best solution?