Get file path of open OmniPlan document

In Applescript, I can do something like:

set myprops to get properties of document "scripted" of application "OmniPlan"
file of myprops

to get the path to the referenced open document. What’s the equivalent in Omni Automation’s javascript syntax? Or, alternatively, can I execute AS from within an OA javascript?

[I’m working on a variation of the example “Copy Selected Tasks to OmniFocus” plugin, as documented on the Omni Automation website. I have other tools at my disposal and may need to use one of them to pass the info to Omni Automation via the clipboard, but I’d rather stay as close to OmniPlan as possible.]

Any help/tips appreciated!