There are several ways to build a handle for a narrow tang knife like the Master Hunter. If you want to make it with two slabs sandwiched around the tang, just cut a groove in each one as long and wide as the tang, but only half as deep as it's thickness. You can use your Dremel for this; I think you can get a fitting to guide it like a small router. Measure carefully. It's good to have a couple thousandths of "slop", this will be filled in with epoxy later.
Put together, these will fit around the tang. Measure carefully again and drill a hole through each scale to match the hole that already exists in the MH tang (where the lanyard tube is on the stock model). Use this hole for a pin or tube that fits all the way through both scales and the tang - this will prevent the new handle from sliding off. Then basically assemble the whole thing (including the tube or pin) on the tang with a layer of good slow-curing epoxy on all the mating surfaces, let it sit overnight and shape the handle as desired.
Obviously I've left out a bunch of details, but that's the basic idea. Check the stickies in the ShopTalk forum for more instructions or send me a pm with any questions.
You will need to decide if you want to use the stock sheath; if you do you'll need to build a guard that's very close to the original so it will snap securely into the sheath.
Ironwood is great stuff but it's pricy and somewhat tricky to work with. I wouldn't recommend it for your first project. Micarta is a fine choice.
Here's a MH I rebuilt for a client a few weeks ago. I made this one with a solid block of G10 rather than mortised scales, but the general idea is the same.