All(?) maps but the Live Map has a polygon tool that can be used to draw an area, everything in that area can then be added or removed from the VGPS.
The plan was to release that for the Live Map as well last weekend, but we did not manage to get that far. We just need to adjust the code a bit. This will be implemented soon.
PS! The polygon tool doesn't work well (not at all) with touch devices.