While they both use CDMA, I'm not sure the band range is the same. I do know that Virgin Mobile doesn't flash their phones for their own network like other Prepaid phone plans do, such as TracFone. While you may not have to take extra steps for the phone to work on the network, you may run into an issue if the company doesn't allow you to add the EMEI number from the phone.
Theoretically, any rooted CDMA style phone should work, so long as it is compatible with the network you're routing it to.
Hope that helps.