Lizard,
I'm pretty sure it can be done, in that manner I did. As the string (around the tips) prevent the wood from splitting. The horizontal string at the belly prevent the cutting in. Drill a hole with a diameter just to fit the string, sand out carefully and round the edges of the hole.
I wouldn't do it with soft wood like yew, eastern red cedar, juniper.
edit:
Just remember, I have seen African bows (long bows, not short San bows) with a drilled hole in one tip. But the string is only secured by a big knot on the back.