We don't really expose our web services through an API or anything like that.

You're best bet is to either use Web Access in an embedded iframe or launch WA through a URL and have your users manually import through the Web Access UI.

Its possible that, in a future release, we could provide URL syntax for importing a document, similarly to the way we provide URLs for launching Scanning. However, that is currently not supported.

This post gives a little bit more background on the issue.