This answer is not quite what you were asking, but I think it may still be useful / pertinent for people reading this question.
If you install the MZTools add-in to VB6, it has the ability to add line numbers in code to each line of each procedure / function / sub / etc.
This can be invaluable when trying to capture error information and you want to record the exact line number where the error originated at runtime. This is not needed in the IDE, but is very useful when trying to debug a compiled component in the field.
Edit: MZ Tools used to have a free version 3, which seems to no longer be available. But it worked well.