I’ve tried to find a plugin for this, but couldn’t.
I also tried to follow these instructions to manually install it, but the link is dead.
https://techknowhow.library.emory.edu/blogs/sturnbu/2011/05/12/netbeans-7-and-python-ide
Is there any other way to install it or is it not possible in netbeans 7.1?
The following link should work (add it into your plugin repository list as said in your given source):
http://deadlock.netbeans.org/hudson/job/nbms-and-javadoc/lastSuccessfulBuild/artifact/nbbuild/nbms/updates.xml.gz
But keep in mind that the Python Plugin is still buggy for Netbeans 7.* :
http://wiki.netbeans.org/PythonInstall
Good luck!