We have a water bottle beside the toilet, since we have different "parts" I've used it to try to explain to him what to do laugh

The diaper-cover over his boxers is a good idea!

I tried a cloth-diaper insert in his potty this morning & he actually liked that! But didn't have to go... . He's having a nap now (-phew!- it's been a crazy morning!) we're going to try as soon as he wakes up smile.