what do you mean hard wire it? do you mean by passing the receptacle on the ballast and wiring the power wires directly to the wires inside? well, i don't see why it wouldn't work or can't be done. just make sure the ballast has been sitting for a few days with no power because they can hold a charge still and zap you.
just carefully open the ballast up and cut the wires from the receptacle then get a 240v power cable that fits and cut the end off. then strip all the wires(Should be 3, positive, neutral and ground. then splice each wire with its corresponding one inside the ballast and cap it with a wire nut. then tape the connection with electrical tape to insulate it all.
For the fuse part, i don't really know. maybe you could get a fuse holder from radio shack(costs a couple bucks) and just put it inline with the positive wire. make sure everything is secure since its a high voltage.
but that is how i would do it. i have a lot of experience in diy electronics and stuff of that sort. so i could help just pm me