If you're making a portable you probably need something to watch it on. (Unless you want to guess what's happening in the game, but I wouldn't advise that) Anyway, this forum is your "Hacking a pocket TV/screen" one-stop solution. Share your experiences and knowledge here.
Even at that I would not know what kind of pot to get. Does anyone have a working Hip Gear volume knob that they can look at to measure the ohms on so I can know what to buy.
i think anything labelled as an "logarithmic volume pot" would be ok. i think typically they are 250k or 500k ohms. basically you need something that is zero at one extreme (max volume), and a pretty high number at the other extreme ([almost] no volume)
however i speak from experience with guitars, which have incredibly weak volume signals.