Comment 120 for bug 1073433

> 1. Will I have to download and install a compiler and a linker?
Sure:
sudo apt-get install build-essential

> 2. Will I have to recompile the kernel to use the updated
> NetworkManager?
No, just network-manager:
sudo apt-get build-dep network-manager
apt-get source network-manager
cd network-manager-0.9.8.0

First of all I would suggest you to check that original package
can be build without any errors. For dpkg-buildpackage
I had to disable test (debian/rules file, --enable-tests=no
instead of --with-tests in ./configure invocation)

fakeroot dpkg-buildpackage -b -uc

Successful build will finish with .deb files created
in the parent directory.. Edit .c files as described
in Comment 114. It is better to edit debian/changelog
file as well and add an additional entry to the top of the file
with another version suffix. This step will allow
to avoid confusion which package is installed.
Again

fakeroot dpkg-buildpackage -b -uc
(option -nc can be added to compile only updated files)

You should have new .deb file that can be installed with
sudo dpkg -i ../<exact name of network-manager_0.9.8*.deb>

The details can be found in
http://www.debian.org/doc/manuals/maint-guide/build.en.html