well the easy way is to put level req on PoK itself - like level 45...
This of course will prevent all through travel as well.
What you could do, is to disable the PoK books, and instead give player at appropriate level a free item with click effect of port to PoK
the only other way is to somehow write a perl script that will detect you clicking a portal and check your level. I guess its possible, but I have no idea how =)
one of our Perl expert need to look at this
