I found a Boeing 767 FCOM online. Here’s the answer...
Takeoff Procedure
Do the normal Takeoff Procedure with the following modification:
When engine anti-ice is required and the OAT is 3°C or below, the takeoff must be preceded by a static engine run-up. Use the following procedure: PF
Run-up to a minimum of 60% N1 for approximately 30 seconds duration and confirm stable engine operation before the start of the takeoff roll.