Not via the API but you can via IRC:
For black (Turbo):
> PRIVMSG #channelname :.color #000000
For green (non-turbo):
> PRIVMSG #channelname :.color green
Not via the API but you can via IRC:
For black (Turbo):
> PRIVMSG #channelname :.color #000000
For green (non-turbo):
> PRIVMSG #channelname :.color green