I scanned and printed a wedding invitation on

You could try some commercial stuff for impregnating fabrics, but most probably it will make the colors run right away during application.
The proper way to do it is to print on a special paper with so-called sublimation inks, and then heat-transfer it to the fabric. There are places that do this as a service, or you can try to obtain cartridges with this special ink for your printer and this special medium to print on, if you want to experiment yourself.