Thanks for using Sitefinity.
I guess I'm not entirely sure what you're trying to accomplish here so if you could describe the situation a little more I think that would be helpful.
You want it so when a back end user adds a module item (such as a custom module item) that a pop up appears that allows them to then edit an actual page? You could use an iframe to point to the /PageName/action/edit URL and if they are authenticated and have permissions they will be able to see/edit it... I guess I'm just not sure exactly the situation you are in right now. If you give me some more info I'm sure I could help a little more here.
the Telerik team
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