The donation should use P2Pool's patron_sendmany endpoint to generate the transaction.

It's better to send a single large tx as that will payout a higher percentage of miners, and include some smaller ones that would miss out on smaller amounts.

If we get to a 1BTC commitment level, I'll provide an address for the donations, and then link to the patron_sendmany transaction in the blockchain to prove I sent it.

I'll send with a minimum payment amount of 0.0001 BTC (right now that would pay 83 of of 93 miners with a share in the chain).

Then I'll build the online form to interface with patron_sendmay and add it coincadence to make it easier for folks to donate to P2Pool miners

patron_sendmany: https://en.bitcoin.it/wiki/P2Pool#Donating_to_P2Pool_miners

endpoint example: http://minefast.coincadence.com:9332/patron_sendmany/1/0.0001