Hi pjrake,
well I see a few options:
1- the simple one is to buy a line splitter that you plug after the Live Line out, send one signal to the FOH and the other to your monitor.
2- if the FOH or your monitor can use an S/PDIF signal, the S/PDIF and the Line out carry the same sound simultaneously;
3- I do not recommend this one, but in the mean time it could work: use the line for the FOH and the headphones out to the monitor. Be careful with the volume of the headphones out, it should work.
4- if you use an amplifier and you want only your guitar sound into the monitor, you may consider using a small 1X12 guitar cabinet and plug it to the THRU output of the Live. This way the guitar cabinet is your personal monitor, you can use a stand to make it aim at your face, like a wedge (sorry if this is not correct english, I shouldn't work on saturday night ^^). We have a lot of guitar player that use this option on stage, to keep the "feeling" of the guitar cab.
Well those are the option that come immediately to my mind, maybe other can think to a better solution.