(Google probably directed you here). Please use the more updated guide for installing on Media Temple’s Grid-Service here: http://www.magentocommerce.com/wiki/mediatemple_installation_guide_-_grid_service

It is possible to install Magento on Media Temple’s (mt) Grid-Service (gs). It’s all about finding the enabling mechanism for PHP 5. Once you find it, it’s actually very easy.

UPDATE: The Grid-Service’s version of MySQL is not compatible with Magento. You may be able to get this to work with an off-site MySQL database. Alternately, a MySQL Container through (mt) might have a newer version of MySQL, but there are no guarantees.

First, upload Magento to your (mt) server, on the domain you wish to run Magento. After you do that, login to your (mt) Account Center and go to the WebControl by clicking the [Admin] button for the appropriate domain.

In the WebControl, you will find the (gs) GridControls. On this page, look for PHP Settings, most likely 5 rows down, in the middle.

Click it to proceed the the PHP Settings page. Here, you will see the option to choose either PHP 4 or PHP 5 for each of your domains. You need to select PHP 5 for the domain you wish to run Magento on. Don’t forget to click Save!

After you have saved these settings, you should at the WebControl page. If not, make sure that you did save your settings and then click the “Back to Controls” link in the upper right hand corner of the page.

Now setup your database by going to Manage Databases (6 rows down, left-most column). Click the Add A Database tab, then enter your desired name for the new database and leave the default as a MySQL database. Click the blue NEXT button, and you should be back at the main Database List page. You need to copy or write down the full database name, as (mt) prefixes it with your account name before adding your chosen name.

Now click on the Global Settings tab to setup a database username and password. Create one in the Add Database User section by entering a username, a password (which has to be at least 8 characters), and clicking Save. Please sure to write down these values used so you can enter them during the Magento install. Now, in the Manage Database Users section, click the Permissions button for the new username you just created. You need to select Read/Write access to the Magento database that you created earlier, and click Save Now.

Finally, you will need your MySQL hostname for Magento. (mt) does not use the standard of “localhost” as the MySQL host, instead they use an address similiar to internal-db.s99999.gridserver.com. The hostname that you need to use is listed under Internal Hostname, in the Your Server Info section (at the top of the Global Settings tab). Make sure you copy down this server address.

Now back to Magento. Open up http://www.domain.com/magento/ (or whatever your install location is). Voila, it should be running! Now review and approve the terms, and click through to the configuration page. It should look something like the screenshot below. I don’t have SSL yet on this install so I used http and 80 as the secure connection.