i don't use a 'gut-hook' but if you want to, if you make the cut from the top down you will be going with the grain of the hair and it'll be almost like a zipper. this is opposite to the way I use my knife blade tip positioned between the index and middle finger of my off hand and start at the bottom and guide the blade up.
If you try going 'up' the same way with a gut hook, you will be going against the lay of the hair and having to continuously stop and clean the accumulation of fat and hair from the crotch of the gut hook, and it more than likely will take the edge off pretty quick.
a lot of guys laugh, but I wear disposable gloves now, I find that it actually helps grip slippery innards and don't mind that it makes clean up faster either!
there are a few good dvds out there that I wish were available when I started, oh wait, dvds hadn't even been thought of then jeepers!!!
anyway, you'll watch a few videos on youtube and talk to some guys and get out there and as mentioned it'll likely take you a 'tad' longer than everyone else on the planet it would seem, but when you're finished it'll be one the great memories you get to keep and share for the rest of your life!!
all the best and like an old timer once said to me," I'd worry more about finding a deer first and getting it on the ground before frettin' about taking it apart"
TB