To install/upgrade any software on your dedicated server, you will need administrator/root access which can be requested via your 123-Reg control panel:
Scroll down to the Dedicated servers section, select your server from the drop down box and click on Manage.
Click on Request Root/Administrator Access.
Please note: That once administrator/root access is provided, technical support is withdrawn, as per the disclaimer. We will only support the hardware in these cases.