Marking Political Contributions as Gay Money

Back in the 1980s, activists rubber-stamped US currency "Gay Money Gay Money" to make a point.

So, I'll ask: How can LGBTQ and allied people mark our political contributions as "Gay Money"?

During Howard Dean's 2004 primary campaign, when grass-roots supporters were sending small contributions, LGBTQ folks were urged to add a specific number of cents to their contributions, to mark them as "Gay Money". (The cents number was the date Governor Dean signed civil unions into law.) Can we adapt that technique? Is there a more effective one? We need a grass-roots, easy-to-do method, with no need for a middle-man bundler.