Making the calls to your context-sensitive topics is basically a job for the programmer, not the help author (you may be both, of course). In the help itself there is no difference between context-sensitive topics and popups and normal topics and popups – the difference is how they are called from the application.
The HTML Help CHM files and Visual Studio Help files generated by Help+Manual are fully standard-compliant so you can use all the standard procedures for linking to and calling context-sensitive topics.
Context calls to WebHelp are made with regular URLs. For details see Application calls to WebHelp.
Context-Sensitive Help & Popups (Reference)