$ sudo apt-get install mono-devel monodevelop mono-tools-gui mono-tools-devel subversion
Afters this you should be able to download the latest source via subversion, compile and install Paint Mono via…
$ svn co http://paint-mono.googlecode.com/svn/trunk/src paint-mono
$ cd paint-mono
$ sudo make install
There won’t be a icon inside your application menu for Paint Mono, the only way to start the program is by executing the following command.
On your desktop Paint Mono should now look like this.