I've tried "##778#", "##778 send", and "##778# send" but every time it dials the number giving me a "Welcome to Verizon..." message instead of opening the provisioning screen (except for option 1 which does nothing).
This may not be what you're looking for (I can't find any options for EPST in this menu) but give ##7764726 a try. The password is 000000 (six zeros) and it should bring up a menu with 9 different options. Maybe what you want is in there somewhere.
I know that using option 4 and setting EVRC-B will make your call quality better. Normally it's set to EVRC.