The only times that I have used a prop shaft requiring a hole that small has involved plastic kit conversions and building my own prop shaft assembly, and they have always been a straight simple hole in a prepared spot. If this is for anything other than a very small model (and 4mm ply says not), then it would normally want, as Colin says, a prop shaft assembly with a 6 or 8mm outside diameter tube.
Use a drill of the right diameter, drill in the centre of the shaft exit, when a hole is created, twist the rotating drill to elongated the hole with the splines of the spinning bit until you have one the right shape to accept the tube at the angle wanted. The tube will need fixing in place, epoxy does that while at the same time sealing round the tube.