No. USB support on the iPad is limited to cameras, keyboards, some of the lower powered USB sticks, and a few other misc devices. There is no support for a modem connection.
If you use the USB modem with a laptop, it might be possible to share the connectoin via the laptop's wifi. I can do this on a Mac, and am pretty sure Windows 7 can do the same thing. It would be redundant and awkward.
What you could do instead is upgrade your USB 720 modem to a Verizon MiFi hotspot. This can be connected to your computer just like the USB720 modem, or it can operate solo as a WiFi network that can have up to 5 devices connected.
I don't know what, if any, difference Verizon would charge plan wise. You would have to ask. To save cost you could look around on eBay and other sites to see who is selling used models.