can a motorola razor v3 be flashed from cingular to boost mobile?

Flashing is suitable for CDMA mobile models only.If you have GSM locked phone means,No need to flash your phone.Just unlocking is enough.
You can unlock your phone with a help of your service provider or else try to buy an unlocking service from any one of the online unlocking service provider like Mobile-Unlocker.com
After unlocking you can't use boost service.Because it's CDMA carrier.Your phone only supports GSM carriers only.