man just chop a sample up and play it... adjust the tempo till it sounds good!
i never understood these "how do you find tempo of song?" threads.. cause like.. its just a feeling man.. its either on, or its not.. just mess with it till it sounds good!
i'll pick a BPM.. say.. 92.. take a 2 bar loop, chop it up into quarter notes or eigth notes or whatever... then i'll mess with the pitch of the sample till it fits the bpm, or ill just mess with the bpm till i like the groove. you can also sometimes get a cool swing if your bpm is a little faster than what the original sample is ( and i know this not from #s, but from the feeling of it)
i swear, sometimes people get too caught up in numbers and %'s and rates and frequencies and shit.. make somethin that feels good, sounds good, and makes people smile (or cry or whatever, depending on your goal

)
/end rant
sorry - there was no disrespect or hate intended in this post, just venting a little.