Just declare a button handler on the last page that runs the checks and
either changes the page/sets the focus or proceeds onward to save the
data or whatever. Personally I get really frustrated by this sort of
behaviour - I click finish and it takes me several pages back and then
says something is wrong - if at all possible I always try to:
a) Group related data together on the same page and
b) Validate as the user populates the page.
Then I can disable the Next button until the data on the page is all
valid, highlight say in Red any invalid data and tell the user what is
wrong as they go. That way you can not get the situation where there
are errors on several pages and you have to, say, go to the first, click
next 5 times to get to the end, go to the second problem, etc.
Gadget/Steve