Wrote an article on this when it first came out. Here is what I do.

on help do myhelp

then

at the start of each form I set a public variable to the name of the help page for that form.

then the myhelp procedure calls hh.exe with the chm file and the further parameter to start at the page set by the public variable.

Tada! Instant context sensitive html help.

If you need exact code let me know