workinman

long story short i was putting my 96 4.9 back together when i overtorqued the valve cover bolt and snap . now i dont have any threads to bite with vise grips. any suggestions on removal preferably with out pulling valve cover back off. its an inline 6 i broke frontmost bolt. will there be any type of damage/ performance issues driving with out it for a day or two other than possible oil leak. i have work in a few hours so any quick temporary fixes are appreciated also. thank you.