Now I know that the code editing enhancements and the REPL window work just fine. But profiling and debugging, which depend upon sys.settrace, won't work for tasklets. Tasklets being the main attraction of using Stackless Python.
Here's a page talking about debugging in Stackless http://www.disinterest.org/resource/stackless/2.7.2-docs-html/library/stackless/debugging.html
I think from the PTVS stand point this would involve editing visualstudio_py_debugger.py to detect that it's running on Stackless and add the appropriate code and making sure it works.
If debugging and profiling support could be added as working OTB then it would be great.