Plug the wireless USB cable of your Rock Band drum kit into an open USB port on your computer and power up your computer.
Download and install Matt Ground's rb2midi (Rock Band To MIDI) software. Assign each pad of your Rock Band drum kit to the General MIDI Drum Map represented in the rb2midi interface. The rb2midi software handles the mapping, click on each drum sound name and tap the corresponding pad on the Rock Band drum kit.
Download and install a MIDI Loopback Driver to send the messages from rb2midi to your Digital Audio Workstation (DAW) or software sampler. The loopBe1 driver works best with rb2midi, but other options include Hubi's MIDI Loopback Device and MIDI Yoke (see Resources).
Run either a standalone software sampler program or your digital audio workstation (DAW). The Rock Band drum kit is only a controller unit and does not create drum sounds internally. The Rock Band drum kit does, however, send MIDI data that tells software samplers or electronic drumming software to play sounds.
Configure your software sampler or DAW to receive MIDI data from the MIDI loopback device by assigning the driver name to the MIDI receive port. The MIDI configuration of most DAW and sampler software is under "Preferences > MIDI or Devices > MIDI", but you may need to consult your software manual.