Idiot proof - pre OBD diagnostic codes

[skatedees]

So I got this: http://mc.mmc.ru/tech/obd_sub.html

Is this idiot proof? Can I do this without messing to many things up?
I tried searching for similar info and came up with noda. Can anyone tell me what's in store for this action?

Thanks

[Huffer]

It's the only way to do it without going to a dealership. It's not foolproof however, because it's easy to mis-count the flashes.