I was very pleasantly surprised to find this works – coincidentally – twice this week someone has asked this question – can I open an XPage in XPiNC directly? I thought the answer was no……and not for the first (and/or last) time I was wrong.
The answer lies here – http://www-10.lotus.com/ldd/ddwiki.nsf/dx/Domino_Designer_URLs_for_XPages
To prove it I created a plain XPage and added the firebugLite custom control
The following XPiNC URL
notes://copper/882579C70057C4C2/aLaunch.xsp?OpenXPage&marky=me
Pasted that URL into a browser and that successfully opened the XPage in question. I was able to show the location.href and therefore the Query_String passed in like this:
Sweet !!
Xomino 
It’s always interesting which nooks and crannies each of us hasn’t gone down. With our main app having been designed as XPiNC only, that was well-known here. I even have an ExtJS grid based off your examples that I have them load in the browser, but that double clicks open the old Notes document.