I'm confused as to what you want to do... comments simply don't
exist(*) outside of the original file, and the compiler wouldn't
assume they are code anyway, so no "step into" short of edit-and-
resume and uncommenting it.

The exception is the triple-slash xml comments, which are optionally
bundled into the documentation xml file; if this xml file is present
for a referenced assembly, you can see these comments in intellisense,
or the "show definition" view.

Can you clarify what you want to do / see?

Marc