running multiple sites from one instalation of CI on Media Temple

[eluser]Yorkshire Pudding[/eluser]
Hi, I hope somebody can help me with this.

Basically, I run a number of domains, on Media Temples Dedicated-Virtual 3.5(Extreme)server, that run on the PHP Codeigniter framework. At the moment I have a separate installation of the framework for each domain so that every time I need to make an update to the framework I need to do it for each domain, which doesn't make any sense. What I'd like to do is run all the sites off one installation of the framework. In addition to this, most of the domains use a lot of the same images (pictures of products) and every time I want to change an image or upload a new image, i have to do it for every domain. Again, this doesn't make a lot of sense to me and was wondering if anyone had a solution to this.

I have searched the internet for a few soloutions and have found this one for the multiple sites running off one instalation: http://www.askaboutphp.com/tutorials/88/...stall.html

This makes sense in relation to my local server but was wondering if anyone could point me in the right direction of how to administer this on a media temple server in terms of pointed each domains to these shared resources.

Thanks for any help in advance