Installing Mag Release Into DIP Bottom Metal

[legaleagle47]

I understand the slave pin idea; however, I have not seen any explanation of how you hold the mag release and spring under compression and then slide that assembly into the trigger guard before you can insert the slave pin, right? The long leg of the spring must be compressed against the front part of the trigger guard, correct? So, how does one hold that compressed spring in place w/o it popping out of the mag release lever before you can insert the slave pin? I'm sure I'm missing some essential but easy step. I'm not a machinist or gunsmith either. Thanks for any tips.
KS
E