Hi,
Not sure if this is the right spot for this question. Mod's please move if needed.
I plan to install a port of OpenBMC by Raptor Engineering onto a Asus KGPE-D16 Opteron-based motherboard
https://www.raptorengineering.com/coreboot/kgpe-d16-bmc-port-status.php. However, it requires the installation of a 20-pin ARM debug header in the unpopulated AST_JTAG1 footprint as shown in the picture from Raptor Eng.

I've seen suggestions to use pogo pins (e.g.
https://www.cfeconn.com/connector/20-pin-pcb-pogo-pin-connector-factory) to interface with the debug header pads, but I'm not sure how to keep them in place.
Hence, I'll bite the bullet and install the header. I don't wish to damage the board as I would need to first clear the plated through-holes (eyelets) of solder without damaging surrounding components. I've searched online and not found anything specific to what is a reliable technique for clearing through-holes on motherboards. From what I've read, because motherboards have typically ~16 layers they can absorb a lot of heat so preheating is recommended.
Q. What is the suggested technique for clearing solder from eyelets of multi-layer motherboards like the KGPE-D16?
Q. Is preheating recommended? If so, how to do it correctly?
Once the through holes are cleared I imaging soldering the header into place would be like soldering any other PCB.
I have access to a decent Hakko soldering station, solder sucker, solder pot, desolder braid, smd hot air gun, heat gun, etc. I imagine it does not require expensive specialised equipment, just good technique. Your advice and maybe a video of a true master at work would be appreciated

.
Thank you.