I cant say for sure, as i have a Droid Eris (Verizon version of the hero) that i used this guide to flash over, with different 2.1 root rom of course. but there is a setting in "Settings > Call > Voicemail Settings" that i changed to *99 for cricket, i havent recieved any VM yet, but i assume this should get you working, since verizon uses a different vm number.
And on a side note, i had issues getting my phone to *228, i was dumb and factory reset the phone before flashing, and it got set to Verizon stock unactivated, i had to modify my IMSI_S in QPST to my MDN that i obtained by calling a Cricket rep.
May help someone else.
Talk/Text/MMS/Web (only from browser, all apps fail) working from this guide.
And thanks again for the great guide, its a blast modding my phone. I just cant wait for more Eris support since from my understanding hero roms dont work on eris without porting.