Are ya talkin about the bass control hooked up to the amp? Or a separate equalizer all together?
My friend has an amp that came with a remote bass control wired directally to the amp. The remote is smaller than a credit card and can be stuck pretty much anywhere on you dash, just as long as it isn't obstructing the airbag and the cord is long enough...
Otherwise, you could do what a lot of people do and just use your head unit (if it's aftermarket) to control the bass. Most, if not all aftermarket (and oem) headunits have built-in equalizers that control the preamp outputs, which is the source for the amp...
Hope this helped,
-Nate