I've got my sprint diamond working on vzw with data, phone, and mms, etc. Here are some tips.
Activation
If you call a vzw tech and try to get the ESN loaded you won't have much luck. Your best bet is to do the *228 option 3 as previously mentioned in this thread. You must have your SPC set to 000000. If you haven't loaded the VZW PRL you may need to dial *22899 instead of *228.
Roaming
To get rid of roaming I loaded the vzw ERI and a modified PRL.
take a look at these threads:
http://forum.ppcgeeks.com/showthread.php?t=39985
http://forum.ppcgeeks.com/showthread.php?t=20090
Data
If you are having trouble with data verify your MIP settings. I had trouble getting my AAA and HA shared secret keys populated. If this happens then you should call vzw tech support and request a DMU reset.
MMS
I loaded DCD's cab of Arcsoft MMS with VZW settings on a ROM without spring picture mail. I found that I had conflicts with sprint picture mail if both were installed.