They do have information on cleaning/ flushing, but your post brings up one beef of mine, organization of their web site(s). It seems (I could be wrong) that this is part of Walker’s mandate. If so, he’s got a huge job because IJM seems to have stuff spread over 3 or 4 sites!
That said, I love their ink and the support here is usually pretty good. (Sometimes you have to pester).
As for cleaning one channel, the only thing I’ve heard about is to use QTR to print one colour. But, according to Walker and other things I’ve heard, if you’ve got blocked nozzles, that method is hard on the head and it’s better to use the power clean.