You could go into a store that sells the remote and see if they would let you borrow the remote for your purposes. Maybe they would charge only a small fee. Alternatively, you could bring your Pronto into the store preconfigured with about 16 or 20 or 24 blank buttons. You might label them Test1 through Test16 (or however many you want). Then use their Lutron remote in the store to learn the different buttons many different ways (short touch to long holds). One or some of them might end up working for you.

I was able to borrow a Lutron remote once (one with 4 scene buttons and raise, lower, and On/Off). I was able to finally learn the buttons to my Marantz RC9200 where I could get my Spacer lamp dimmer to set new scenes using the 9200.