Please check out Appendix B.1 and B.2 of the Spider Jam Pilot's Handbook for information on using the FBV pedals with the Spider Jam amp:

  http://l6c.scdn.line6.net/data/l/0a0600724a334af318bd2fcd4/application/pdf/Spider%20Jam%20Pilot's%20Guide%20(Rev%20F)%20-%20English.pdf

  Please Note:  The newer FBV Shortboard MK II pedals are a little different than the older models.  Function 1 on the Mk II pedal is FX Loop on the old Shortboard, and Function 2 on the Mk II pedal did not exist on the older Shortboard, so it does not do anything or add any functionality.

  Regards,

  Line6Hugo