Aloha,
What we ended up doing was 3d print the spool and guide.
On the spool where the two bolts goes through to assemble the two halves we put in a large enough cut out to accommodate the strapping as well.
You just sew the end of the belt to make a small loop for the bolt to go through when you assemble the spool the belt is on.
It keeps the belt quite flat when spooling since the loop is below the barrel where the strap winds up.
It can feed either direction. The second part is a guide to keep the belt centered while spooling. Though the sides were high enough that it wasn't really necessary.
Here is a picture of the spool on the robot, you can zoom and hopefully see.
http://www.chiefdelphi.com/media/photos/42355
I will post a picture of just the disassembled spool and update this with the link when it is available.
We ran this through two regionals and the champs and never had an issue..
Still working today.
Any questions?