Sorry I'm late to this party....
Glory Hallelujah is Warlord's ACW supplement for their Black Powder rules (which is kinda what Pike & Shotte is based on). Given that you're gonna go with Pike & Shotte, I'd suggest just doing Black Powder, which is essentially the "Horse & Musket" version of that rules stable (Hail Caesar, Pike & Shotte, and Black Powder.
Glory Hallelujah is not required to play ACW with Black Powder. but it doesn't hurt to have. If nothing else, it has scenarios in it...