If you dont have a drill, you can go the ghetto way and use a flat head screwdriver and a hammer, smack it at an angle to the rivit head, they come right out and pot the rest of the rivit out
Drilling is how i did mine, if im not mistaken (Please correct if i am) a 1/8th drillbit is exactly what you need to do it with unless you dont have standard sized rivits.
If i might make one suggetion though, Black and Decker makes a metal drill bit (i cant think of the name of it now, but its pritty unique looking) that has a tip that is half the size of the main shaft, it makes it SO much easier to drill out because the little tip digs in first and makes sure you dont pop out of the hole.
Yes, you drill them out using a bit that is the same size as the hole the original rivit was put in before it was pulled. 1/ 8th inch is typical.
Beware of the spinners. If the whole rivet spins inside its hole when drilling it out, its a pain to remove. Use more pressure. Use sharp bits.