I don't play the guitar, I'm a piano player. I know some theory, but mostly I just read music in front of me and play it.

What I did learn about transposing was pretty easy, and it doesn't involve naming everything along the way. For me, transposing simply means reorienting myself to the place on the keyboard where I want to play, and sticking with the same pattern as is on the sheet music.

Learn the scale. (I can't tell you how to compare the guitar to the piano.) I'm not talking about C-D-E-F-G-A-B-C. I'm talking about how the scale is accomplished. There are different types of scales (that gets into theory stuff, so I'll stop here). I found a web site with a "free piano lesson" that does a tidy job of explaining this. It's here. The scale I'm talking about is how it is played, using whole and half notes. A major key is played as whole-whole-whole-half-whole-whole-whole-half. A whole note is from one white note, past a black note, and to the next white note. Two white notes (E-F) count as a half-note. No matter where you put your hands down, in whatever key you happen to end up, if you follow the notes on the page but stick to that whole/half formula, you'll be "transposing." (again, visit that web page, it might help).

If I learned this on a piano with 230 strings, how hard can it be on a guitar with six or twelve?

Good luck!

SRS