Well, the easiest, down & dirty way to do it would be to twist one of each ignitor's leads together and then attach the alligator clips to the twisted ends.
The second and more reliable way is to build yourself a clip whip. This is simply some wire (I use about 12" of speaker wire) with an aligator clip soldered on each wire lead. Use one pair of clips and a piece of wire for each motor you'd like your clip whip to support (ie. mine has 6 lengths of wire and 12 aligator clips to support a 6 motor cluster). Then take the same lead from each wire (it helps if you use wire that you can identify which wire goes to which clip like 1 black wire and 1 white wire etc...) and twist them together. Then solder the twisted wires together and then use a multimeter to check that you have continuity at each set of aligator clips.
Hope this helps,