Umm, yes and no. The only V3 RAZR explicitly supported by iSync is the GSM version fielded in the US by Cingular, and usable on the T-Mobile network.
That said, there are workarounds.
While this has nothing to do with synchronization, it is an issue for Verizon subscribers and may well be one for you too: the V3c is a V CAST device, and as such, cannot be used as a CDMA wireless modem to connect to the internet. Many Verizon-supplied mobile handsets and smartphones do include a DUN - or, Dial Up Networking - profile, but V CAST devices do not. I mention this because the lack of DUN support is a 'deal breaker' for many Verizon subscribers.
With regard to iSync, you'll need to use a plug-in to provide the additional support needed. Nova Media provides a package of such plug-ins, but the current paid package does not appear to contain support for Motorola handsets, though such support simply may not be listed in the documentation. Their FREE package does include specific support for your V3c, but it does not appear to be available for download at the present time. Send me a message, and I'll reply with a copy of the FREE package.