Clutch basket removal without fancy tool

Any handy tips on how to loosen a possibly overtightened clutch basket nut? Ive tried in gear with brake engaged using a breaker bar on the ratchet, but it felt like I might be stressing the gear so I backed off. I'm not keen on drilling holes in one of my metal plates to make a brace (dont have any spare plates).
So Im pretty much looking for a magic trick yeah?

Guys on the ZX12R forum use an impact wrench to shift the nut and do it back up.

While its in gear? Ive got a rattle gun (impact driver) but wasnt sure about the stress going back through the gears?

Ok, ive tried the impact driver both in neutral and in gear with rear brake engaged. Still not budging

have you unstaked the nut, they are a little dimpled in section on inner edge of nut, small screwdriver , couple of whacks prises it open, the old cold chisel method[ hit the nut on one of the six sides in anti clockwise direction, slowly undoes the nut] works well, but you need a new nut then, get a decent rattle gun, it will come off

"Decent" rattle gun might be my issue

Get hold of a few old clutch plates, and bolt them into a pack together.
Insert this in the housing and rattle (better than an impact driver, less axial overlaod) away with the rattle gun (nice name that )
If your rattler is dodgy then pour some oil (EP90?) in the air inlet - then rattle on.

Thanks BurP, I just got it sorted before I read your post, will try oil up the cheap rattle gun  
I didnt have any spare plates, but I did find a magic trick!
Stuffing clean rags tight in between inner and outer basket using screwdriver locked it up nice. Then I went with the fat blunt chissel and peened the nut lefty loosy