Thank your god, this is not as hard as installing Eduroam on Arch Linux. First, you need to download all the necessary files (the certificate, your user's certificate and your user's key from the UM website; IT Support » Manage IT Account » VPN Access » Download your VPN configuration files).

Then it should be “relatively” straightforward. From Network Manager » VPN Connections » Configure VPN. THe main configuration screen should look like:

There are a few gotcha's which you need to address. First, from your configuration files /etc/NetworkManager/system-connections find the config file and under the [vpn] section add tls-cipher=DEFAULT:@SECLEVEL=0. This is because recent versions of OpenSSL (on Arch) will not allow the legacy version enabled on the server.

This should allow you to connect to the UM VPN, but alas no internet. Fret not. In the Advanced button of your VPN connection, under the General tab, make sure Data Compression is checked with Asymmetric LZO as options, otherwise you will not be able to browse the “normal” internet.