I never saw this old post. It is definitely possible to configure custom embedded color coding like you've described. The color coding engine in SlickEdit was redesigned in v21. This new engine does support doing what you want. It's simple to do but not obvious if you've never done it. The best thing to do is to look for an example for any other language.
Look at the color coding profile for D and view the token definition for "q{". It's near the bottom of the Tokens tab. Select it. That click the Embedded tab to see what settings it's using. This example is D embedded in D but you can specify a different language to embed. Hopefully, this will make some sense to you. If not, I can help.