AFAIK the only way to integrate 3rd party sensors into a HWQS program is to wire them to a QSE-IO.
On the other hand the most convenient way is more than often to wire these to CCI inputs on a keypad.
On a related subject, being able to copy and paste CCI programming would save me A LOT of time. Programming conditional stuff on these and not being to copy it to the next one is a PAIN.