Not sure which wires go to the starter and the ignition switch, the easiest thing would be to just connect those two together.
Lacking that, there must be wires by the seatbelts to tell it if they are fastened. If you connect these two wires it will think the seatbelts are always fastened.
Csaba
'71 124 Spider, much modified
'17 124 Abarth, silver http://italiancarclub.com/csaba/
Co-owner of the best dang Fiat parts place in town