Xterm supports a number of options including keybindings, here's my fix. This will send a "page up" or "page down" character sequence to your terminal if you hit page up or page down, respectively. Shift+pageup still works as expected (actually scrolls)
! Override default action when hitting pageup and pagedown - actually
! send the ANSI code for page up
*VT100.translations: #override \n\
~Shift <Key>Prior: string(0x1b) string("[5~") \n\
~Shift <Key>Next: string(0x1b) string("[6~") \n
Put that in your .Xresources and load it with:
xrdb -merge .Xresources
This file should get loaded automatically when you login through dtlogin, but I haven't tested this yet.