I see you've waited awhile for an answer to this question. For a positive response that is reasonable you'll wait a lot longer. My short answer is no. The longer answer is that you can delete the outline format and add the smaller one by selecting add 2-d lines and get it from the library. But all the work you'll go through to rotate the printing options etc, hardly makes it worth your while. So while it can be done, it's not pretty.
I like the NO answer better.
I know this thread is very old, but I'm new to PADS, and I've just placed an IDEA to allow different sheet sizes in a PADS Logic schematic, even old Orcad 9 allowed this, it is just a wrong design decision not to allow it.