Should I attempt a 4 spanner job?

[Boris]

It should be possible without the drastic action of a cylinder head removal. you can sometimes drill out the stud in stages by going up by drill sizes and tapping out the final bit, or, getting hold of a helicoil set and doing it this way. You may need to remove the front forks for easier access, especially if you're working at floor level. but don't forget to prop up the bike. Or alternativly take it to your local bike shop they must come across this quite alot and even if costs a few quid it's cheaper than a cylinder head job.
hope this helps.