I didn't use one. I did what LCZ128 did and knocked the pins out. The United one came out very easily while the Hasbro one needed a bit more work. It was actually harder to place the pin back in than removing it, that is where I got my thumb stabbed.
When it comes to pins, I have always found them to be a luck of the draw sort of thing since some come out easy while another can be stubborn. When I fixed my MP Thundercracker's swapped chest panels, one pin came out ridiculously easy and the other took me ages to remove.