I’m looking for this, too. I know last year I was able to do this, but this year I am not. The only reason I know is that each May, we post an Excel spreadsheet on the network that managers use to sign their staff up for a 2-hour class time on one of three days. I found last year’s post and clicked on the Excel link. It just sits there looking silly now, where I know for a fact that it worked before… the sheet is populated and that’s the only way they would have gotten to it.
I decided it probably wasn’t secure in our environment to link to a file on our network share, even if our site is protected. I sent people an email instead, instructed them to pull up the file themselves from the network share, which they found easy enough to do.