I would like to second the suggestion for being able to manually request an IP range to be scanned.
I have quite a few clients where i would like to be able to do a probe from their domain controller that is hosted off site and on a tottally different network than the on site router (f.x. router network is 192.168.1.x and DC is on 10.100.100.1)
I have tried adding a 192.168.1.x IP to the NIC before running the probe but it doesn't work.
P.S. The on premise network is completely accessible from the DC.