Wire in a regular 3.5mm plug onto these speakers

These speakers are tricky because they require amplification. There was a 3rd-party device named "iFire" which allowed any computer with a firewire port to drive them, but it's also discontinued and very expensive on the used market. The best path forward without destroying the speakers would be to source a 2.5mm TRRS adapter that the Pro Speakers can plug into, then chop up that adapter and run it through an amplifier and then a standard 3.5mm stereo jack.

The difficulty will be finding a 2.5mm TRRS adapter that fits into the pro speakers, because the outer ring tends to interfere. Something like this may work, but you should measure to see how much clearance you'd have. You could chop the pro speakers, but the preservationist in me advises against it.