This is the simplest technique I've been able to come up with, based on Gary's and James's initial forays.
Open the upload form and select Share>Add Database .... I find that I have to select this twice but that may not apply to others.
Fill in the data boxes. DO NOT press Validate.
Open or click in a Panorama X database, go to a procedure, remove and replace a character and save.
Return to the upload window, click on Validate, then click on Close.
I have found that, in every case, the window closes and re-opens with the Upload button available.
I've uploaded all of my current stuff so I can't check this but I think that the above steps work only if you start off, not in the upload window, but in one of the already posted files in the sidebar.