I cut keyholes with my router's keyhole bit with the handibot but without gadgets. I also first pocket them out with a regular endmill the same size or smaller than the shank of the keyhole bit. VCarve doesn't support keyhole bits, so I just create an endmill with the exact same size as the shank and use that.
As for entering and exiting in the same point, I just use a profile with a rectangle vector with a length of whatever you want, and a width of something like 0.005". If you specify "Use vector start points" under "Machine Vectors", then the tool will use the vector start point of the rectangle for entering and exiting. Just set your pass depth >= cut depth and it works. It will plunge down, go forward, back, and exit out of the same start point of the vector. Make sure to preview and probably even run an air pass to double-check everything is going to work as expected.