Go into the two player arcade with your main account and a second controller. Use these settings:
Reset Scores: No
Then hit play. Jump down to the lower level of the senate pods with your second controller and then jump off to die. Repeat 100 times. The below video is not mine, but it definitely sums it up for those who like visual aids like me. :)
Edit: Per skittlebiz in the comments:
Luckily my one guy was stuck in between two pods where he would slip down and die, and kept respawning there so all I had to do was set down the controller and watch until 100. So that might be a recommendation - try to get your guy between and toward the front of two pods where he slips down to die continuously.