Multisite DomainMapping Frankenstien.. Or is it possible?

Hi all.

I have read through a few of the posts here, and am now more than ever a little confused.

I work for a small not-for-profit, and we had a few wordpress installs, on various hosts/servers/domains I am hoping that multisite will help with the admin for these sites as keeping up with all of the updates is a nightmare, plus save on the hosting etc

So here is what we have.

1domain.net
2domain.com
3domain.org

I would like to redirect each of these to newmultisitesite.com/1domain etc.
The trick that I would like to make happen though is for the url to stay as 1domain.net in the address bar.

I know this has something to do with domian cloaking (thanks google), but is this possible using some coding and plugins?