I am pretty sure you are not going to get a fix from X10. They make their AHP IWatchout and the mobile viewing apps to work with their VA12A video USB adapter. That limits you to one video stream as well.
I use 3rd party video viewing software (CAM Wizard by ledset.com), which allows me to see 4 screens simultaneously, either with a PCI card (with 4 separate processors - most are one video signal at a time) or with 4 separate video USB adapters.