The key to me was setting that var as bindable and using the HTTPUtil class to retrieve the value from the parameters on the html (owner) page's url. Then the creationComplete() function actually does some work before doing the HTTPService.send().
Thanks for taking the time to reply. I've posted a few things (that I don't see totally out of the ordinary), and it seems to be a bit of a "cold" forum at times. 😞