Dont know how easy this is or even if its possible, i want to slow down a sample to fit in with the bpm of my track, i understand this may affect the sound but it seems like it should be something thats easy to do, like slowing down a track on a cdj
for fitting a sample into a pattern, read this:
http://tutorials.renoise.com/wiki/Instrument_Settings#Sample_Properties
for time-stretching (adjust speed without pitch, or adjust pitch without speed), use the Rubberband tool:
http://tools.renoise.com/tools/rubberband-timestretchpitch-shift