Do you use the equalization to fix recording problems or to modify the response of the headset?
Personally I think that modifying the response of the headset makes no sense. With speakers, equalization can be a useful tool (room problems, resonances, etc.), but with a headset you don't have most of those problems. Headphones are "cheaper" than speakers and there are thousands of different profiles, you just have to try them.
As for DIY, I agree with Mwl168. I can only give you two tips:
Start with something simple (a C-Moy for example) to learn how to soldering and then continue with something more complicated. It was one of the first things I did, buy a good soldering iron and a good multimeter. In the future you will appreciate it.