for tracking at work we use a tape measure (tracking gauges are broken)
get someone to hold it on the front of the front wheel then someone at the back to pull it tight at the back
hold it away from the wheel (at the back)
then move it towards the wheel slowly until the tape touches either the back of the front wheel or anywhere on the back wheel
if it touches the back of the front wheel first you're toeing IN
if it touches the back wheel first you're toeing OUT
adjust accordingly
Jake