You can do so via several methods.

* Voting - You can select candidates for public service who will author or approve legislation that directs your taxes to projects you support.

* Lobbying - You can try to convince public servants and other public officials to enact legislation and/or regulations that directs your taxes to projects you support.

* Campaigning - You can try to convince other voters to vote for candidates for public service who will author or approve legislation that directs your taxes to projects you support.

* Lawsuit - You can try to convince one or more federal judges to interpret existing laws in such a way that your taxes are directed to projects you support.

* Run for office - You can place yourself on the ballot and promise your constituents to vote for legislation that directs your taxes to projects you support.

I think you should, and o should I. Now how do we work out which programs get funded? And what about the other people on HN? In the country?

I think you should get a vote, and have every chance to persuade them to vote your way. (I also think you should listen to others' ideas, just in case!)