I recently had to go though this effort to get multiple zones of IR from the USB-UIRT, so I thought I would create a simple wiring diagram to help future readers who are trying to set this up.
http://forums.sagetv.com/forums/attachment.php?attachmentid=7130&stc=1&d=1220727252
http://forums.sagetv.com/forums/attachment.php?attachmentid=7129&stc=1&d=1220726945