Please don't show anyone where to make the change - if someone can't figure that out, then they have no business releasing code that they have no real clue how it works
These people are going to create copy-pasta clones anyway. If we don't educate them they will be forever without this knowledge. So I encourage you to explain how to make this modification. I am sick and tired of all these clones starting at retardedly low difficulty.
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..
Hmmmm... If it's that easy then it's absolutely silly that these copy-pasta clones start at such a ridiculously low difficulty.
Again, if you have knowledge of how to set the initial difficulty higher please share it. The recent flood of clones is obviously being done by amateurs that probably won't figure this out, and yet will release their coins anyway. So do everyone a favour and educate them. Maybe they will listen.