I'm assuming you can jump the large "batt" terminal and the next to it brown wire "sol" terminal on the starter relay & it will crank. Not sure if the seat belt relay interrupts the yellow start wire power side or the NSS ground wire ground side but if it opens the power side I'd run the "st" terminal on the ign switch to the yellow wire at the "ign" terminal on the starter relay and if it interrupts the grounds side I would ground the "grn" terminal on the starter relay (which will cause it to be able to be cranked/starter in any gear), safety just sayin.