Here's a tutorial on using
shortcircuit that may be useful. I don't know how much you need the features it offers, such as multisampling, but this is the way I'd approach the problem.
http://forum.cockos.com/showthread.php?t=18176
Instead of getting your samples from the download site, you'd record them yourself, but otherwise this is the path to creating a playable instrument out of samples using SC. I believe version 1 is still the preferred choice for Reaper users.