757 vs. 767 They are different
The two types have totally different procedures for P.O. T-O. Vol I Supp Procedures details the actions for each type.
It was pointed out to me that for the 767 the APU is not sufficient to provide bleed air for both the packs and the ADP. Therefore, for the 767 you cannot do an APU-to-Pack takeoff, because there would not be sufficient pressure to operate the ADP (along withthe packs) if an abnormal occurs. Loss of the ADP is a 40,000 pound hit on RATOW for dispatch for some 767s. For other 767s, I think it is still a 36,000 pound hit.
That's a significant penalty. Look it up next time you are in the jet.