Remotely installing Debian using a web browser
wiki.debian.org
wiki.debian.org
From the article:
The idea is booting the target machine with a Debian installation image preseeded with a fixed / dynamicaly assigned ip address that start up a web server that allows the sysadmin to connect to with a simple web browser and perform the whole installation process comfortaby sat at his desk.
For a remote install, you could either configure the IP before burning the install media (as you suggested), or have the installer scan connected USB devices for a known config file name, and load configuration from it. That way, all you would need to do is have the colo tech load a file you emailed them onto a thumb drive, and then insert that into an available USB port on the server before starting installation.