InsOptPages back and forth

I have 3 questions about proceding in InstallOptionsPages:

1. How can go to the next page from a function? So i dont have to push the 'Next' button...
2. How can i use the 'Next' button to go to page4 instead of page 3?
3. Same for the 'Back' button.

No ideas?

to skip a page, call abort in the pages pre function callback

More advanced jumping: http://nsis.sourceforge.net/Go_to_a_NSIS_page