umm...isnt that when u're supposed to do it..?
isnt that why it's called a HOT valve adjustment?

i supposed you could loosen the bolts when theyre cold just enough and then let it get hot...but i just recently did my valves and i beat on my car for like 15 mins, and got it all nice n hot, then got it all off and adjusted, and put it back together...(twice since i kinda forgot to adjust one set of valves, when i 1st put it all together)...and i never had any issues...

 

+2...if you're not sure what u're doing i'd suggest taking it to a shop to fix that...
u may end up slipping off the stud and drilling next to it and making more of an issue than it's worth...worst case scenario - u mess up too much and u may need to end up getting a new head
best case scenario - if THEY mess up too much then they get to buy you a head