well i ordered my q5 from KD which is fixed on a star so i have to heat it up so th led removes from it.
i broke off the whole copper both positive and negative from the magled because i'm not going to use the led anyway.
it's nice to have another person helping. i had the led upside down and had someone hold the copper piece with a tweezer while i used one hand for the solder and the other for the heat gun.
you definitely need steady hands as the space is small that you need to solder to.
i didn't bother with a copper heatsink as the stock had none. just put some thermal compound in between the led and pill.
as a precaution maybe you can test to see that the copper (negative, positive) is correctly soldered on the led by feeding it some juice. reason i say this is because i heard the circuits blow if there is no led in the mag pill so you definitely don't want to power on with no led.
it's pretty simple swap. not as simple as a star swap. just take your time. cree makes a significant bump up in power.