The ERR Mini-Commander II and the ERR RailSounds Commander should fit, that gives you command capability. I'd probably
I haven't looked at the HO PS/3 boards, but those might make PS/3 fit into that little guy. That would be a bit of work as there are no wiring harnesses and the tiny 1mm pitch connectors are somewhat a PITA to work with if you're hand wiring things.
FWIW, that little locomotive is fairly heavy, so it would be interesting to see if the PS/3 HO hardware has the stones to actually do the job.