If the DSP files are text, this is definitely doable. All our code for opening third party projects and/or workspaces is written in macro source. The hard part is support adding/removing files from SlickEdit or handling cut/paste in the project tool window. We try to support adding and removing files for all third party projects but we only support cut/paste for a couple. In the case of Codewright, we'll just convert there projects since the product is very dead.
It is easier to just to write something that converts the project every time you open it. Also, if you write a new command to open just these projects, you won't need to modify any macro source we ship.
If you go the nine yards and do descent job modifying the Slick-C source, then we'll just add it to the product :-)