Dude, don't give in!
(Disclaimer: I don't use protools or mbox, but I wont let that stop me...)
In Protools, do nothing with the track slider while recording. Leave at at the default 0dB position.
Turn down the knobs on the mbox. If you have a Pad switch, make sure it is not engaged.
As you play, watch the track meter in Protools. Above the bouncing coloured meter display, you should see the peaks being displayed as numbers.
You want your peaks to be at about -12dB (that is minus 12 dB). Turn up the mbox knobs until you see the peak at around -12dB. If the signal peaks hit 0dB or more on the peak meter, then you are into digital clipping = horrid distortion. -12dB gives you a good clean track (assuming that the signal itself is not distorted).
If you have XLR connectors make sure they are pushed together - you should hear and feel a click when you connect a cable to the microphone.
Once you have a clean track recorded, you can mix it and worry about final loudness at the very end. Just turn up the monitor/headphone in the meantime.
Hopefully something here will move you along.
Paul