This is a way to get some more recent packages from feisty to replace the older package in edgy.
This does not work on all packages but most smaller packages should work, sometimes its a matter of trial and error.
Fist you have to replace edgy to feisty in the deb-src lines in your sources.list, NOT in the deb lines.
deb http://archive.ubuntu.com/ubuntu/ edgy main restricteddeb-src http://nl.archive.ubuntu.com/ubuntu/ feisty main restricteddeb http://archive.ubuntu.com/ubuntu/ edgy-updates main restricted deb-src http://archive.ubuntu.com/ubuntu/ feisty-updates main restricted deb http://archive.ubuntu.com/ubuntu/ edgy universe multiverse deb-src http://archive.ubuntu.com/ubuntu/ feisty universe multiverse deb http://archive.ubuntu.com/ubuntu/ edgy-backports main restricted universe multiverse deb-src http://archive.ubuntu.com/ubuntu/ edgy-backports main restricted universe multiverse deb http://security.ubuntu.com/ubuntu edgy-security main restricted deb-src http://security.ubuntu.com/ubuntu edgy-security main restricted deb http://security.ubuntu.com/ubuntu edgy-security universe multiverse deb-src http://security.ubuntu.com/ubuntu edgy-security universe
I did not change the security and backports sources; they are not active in feisty yet.
Time to set up the needed packages for creating .debs:
sudo apt-get update
sudo apt-get install fakeroot build-essential
In this example I am going to get the sources and compile a .deb of xchat 2.8.0 from the sources of the feisty repository.
First install the dependencies to make the compile for xchat to a .deb work:
sudo apt-get build-dep xchat
Then make a folder for xchat where the .debs are created and go in that folder and start creating your .debs:
fakeroot apt-get source -b xchat
The sources and other needed files are downloaded and start a compile of debs for xchat.
Now install the created .debs, in my case :
sudo dpkg -i xchat_2.8.0-0ubuntu4_i386.deb xchat-common_2.8.0-0ubuntu4_all.deb
And you have the latest version of xchat installed.