idakz - Sorry, I can't help you there. I know nothing about the 3K's or ChickHEN. I just don't mess around with 3K's.
Kefin - You will need to find 401.pbp. The official firmware eboots can be found quite easily by using Google. Just search for "401.pbp" and look for a rapidshare link. I'm sure there will be about 10 of them.
Mr. Sprinkles - It's all good, don't worry about it.

But yes, if you have a Slim that came with 4.01 or higher out of the box then there is a very high likelihood that it is unhackable. Like 98% chance that it is unhackable.