said 7 months, 2 weeks ago:
There used to be a GREAT service called formulists…unfortunately they shut their doors over a year ago. That service would have done what you needed.
Since you can quickly do a search for anyone who used a keyword in Twitter ( https://twitter.com/i/#!/search/bacon ) and follow anyone on that list in two clicks, that’s probably a pretty decent way to build that list.
Plus, then you get to vet the members before you add them. You never know when a spam bot is going to jump on your keyword.
But, no, I don’t know of anyway to add people to a list automatically in Twitter.