I've always disagreed with that guidebook notation for HoC p3. The crux to me seems like the dogleg start, where it's thin hands. Then it's bomber #2 camalots. Finally there's little bit of cupped hands/fists before reaching the ledge.
Blake, the third pitch starts as that thrutch. It's easiest if you can walk back (and up) till you can reach high for a hand. Once you've mantled that and want to work up and right to the wide crack that Matt describes, there's a key thumbs-up right handjam you want so you can make upward progress. I say key, because you will find it hard if you place your pro there. Rather it's better to place a TCU in the horizontal crack just to the left.
You can also access the top of G-M p3 by climbing the "bonus" part of HoC p3. It's 11a in the guide, but it's really one or two moves that could be easily aided.