It’s trivial to move a bot from one to the other. In the source for CharBotGreen there’s a line
u = "http://twitter.com/statuses/update.json"
Using the Twitter-compatible Identica API you I can just replace that line with:
u = "http://identi.ca/api/statuses/update.json"
The only thing to watch for is that Identica stores names as lowercase and the authorisation fails if you don’t send it in lowercase.
Doesn’t work in Identi.ca:
req.basic_auth 'CharBotGreen', 'sekret'
works in Identi.ca:
req.basic_auth 'charbotgreen', 'sekret'
Thats it though – easy!