You would need to create your own raw transactions with the message already encoded.
How to do that?
or blockchain.info?
View the transaction with the block explorer. Make sure you click the "show scripts & coinbase" link.
This transaction here:
https://blockchain.info/tx/8a754f417dfda84d8fa8a27d67560fd4a0d13c54d3f617ccabae3a473d308208?show_adv=trueI know it has the text:
"The Congress shall have Power... To promote the Progress of Science and useful Arts, by securing for limited Times to Authors and Inventors the exclusive Right to their respective Writings and Discoveries;"
But I don't see it when I click "show scripts & coinbase"