ok, its pretty simple...
1. take your sample you've made (bangin on the table) and make it into a rex file using recyle.
2. open dr rex in reason and load the rex file you have just made
3. preview the file to ensure you're happy that the groove has retained its original feel. you may have to play with the tempo a bit to get it right.
4. click to "to track" button on dr. rex and it will paste the groove as midi to your sequencer.
5. open nn-19 or whatever you want to trigger your new sample from.
6. move the rex midi groove to the track of your new instrument.
7. the groove/timing will be right but you will need to play with the note placement to ensure the right samples are triggering.
NB. i may be wrong but this won't work with the redrum. only nn-19 or the nn-xt.
if you're still having issues, pm me i'll gladly help you out.
peac