I rarely play Beatmania in MAME anymore, it always seemed to have a bit of lag in it and the versions I tried in MAME were so old it got borring fast for me since the play list was so small. I much prefer simfile players for Beatmania (like Stepmania is a simfile player for DDR). I suggest getting MixWaver2 or BMDX. Or get the PS2 game, looks good to me though I haven't tried it yet.
As for spinner use - I suppose you could use a spinner, though I don't think either of those simfile players accepts mouse movement as an input. Mame should be able to do it though. If it doesn't, what you would need to do is look up a mouse-to-key program that will send a key when the spinner is turned one way and a different key when the knob is turned the other way. I've seen programs that do this sort of thing before but I rarely have need for them.
Also, Beatmania is hard to play on a panel unless your pushbuttons are spaced properly like keys (like they are supposed to be for Beatmania). It will be very hard to play Beatmania on a straight button setup.
Needs to be:
[] [] []
[] [] [] []
NOT:
0 0 0
0 0 0
I've tried the latter. Didn't work out for me. Now I use a real Beatmania controller.
Good luck! Let us know how things turn out!