we're not going to talk about my first failed attempt (word of advice, don't try to do it on low quality wood, it will only lead to sorrow), but here's the process that ultimately worked for me:
i started off with a thirty-six by twenty-four inch canvas and planned out everything in photoshop to determine what size x's i needed. i then printed off graph paper with the right sized grid and laid out my design.
with the graph paper taped to the canvas, i then took a small nail and punched holes everywhere i would need to thread the yarn through--all six hundred and six holes (yeah, i counted). surprisingly, this wasn't as time consuming as i had anticipated.
and then it was just a matter of stitching it, using a tapestry needle and yarn. this was probably a funny thing to watch a very pregnant libby do. reaching the letters in the middle of the canvas was particularly challenging.
and here it is hanging in the nursery above the changing table dresser. pretty cute, i think.