i was thinking about the same thing. i think you can use a tuner but it needs to be a chromatic one so you have all the notes, not just the ones guitar strings are.
as i plan on buying one i have a 'technique' i use for the moment. i use an XL but i think it you can do the same thing on a 3000 (not on a 60 because it doesnt have a LPF).
u need your main sample and your bass sample and assign the to 2 diff pads. the one with the bass sound need to trigger both pads so if you press the bass pad the 2 sounds will play. now u set the filter of both pads verry low 0-10 and start tuning the bass up or down. when you start hearing fast fluctations (like and LFO) your getting close. u need to tune it untill the fluctuations slow down and eventually stop then your on the right key.
if you dont understand what these fluctuations are, just lood in 2 looped sine waves of a different pitch, do what i said and you will get it
hope this helped