I have a possible solution for you if all you are trying to capture is the page number.
I was unable to disable mousewheel in the web control and page up/down went out of sync after a few pages but by putting an invisible form over the web control I can prevent the user interacting with it so enables you to provide 'previous, next, enter a page number, home grown scrollbar' type functionality on your main form - the code resizes the pdf so a complete page viewed.
The attached is crude but demonstrates the principle.
Not sure how much of an explanation you require but form1 contains the web control and basic 'select a page' navigation
form2 is the invisible form, I've set a very low level of visibility so it can just be seen. It is a popup (needs to be) and I haven't provided any window placing code so you'll need to open it and drag it over the web control to get it to to its job.
You'll also need to populate the file name control.
I tried it on a pdf with some 3300 pages (mySQL manual) and it was pretty quick going from page 1 to page 3000 for example