The tool u mention already exists.. it's called cgminer.. or cpuminer...

you simply start a few daemons with the -connect option. That ensures it only connects to one node (which is also yours).. then you instruct your rigs to mine on your node.. as soon as you have a height > current blockheight you disconnect one daemon and restart it without the -connect option.. Voilá..

And yacoin, yes I think this has been done..