There are a number of ways around this:
Scrap your switchboard and start a simple menu form from scratch, that way you can have as much buttons as you wan't.
Set-up your switchboard into different menus, which can be accesed from a main menu, look for something like 'goto switchboard' on the button type.
You could try and modify the code, switchboards are actually quite simple forms, each button and text box is named with an number at the end. You should try and make some more buttons on the form first, then get the onclick commands and the switchboard setup commands to recognize these, you may have to add the additional buttons to the switchboard table manually.
HTH
Andrew.