What is the easiest way to automatically redirect people to a webpage based on the URL they originally go to?

My University recently switch to Google apps, which includes google sites, but the sites created have really long URLs, and I would like to make a way to shorten that for other students. Basically, what I am looking to do is, for example, when someone times in:

mysite.com/hpm/calendar they are redirected to https://sites.google.com/a/umich.edu/hpm/calendar

For mysite.com/ANYTHING, I would like to redirect them to the page they just typed in, with mysite.com (red above) replaced with https://sites.google.com/a/umich.edu/ (blue above).

What is the best way of doing this? I may or may not be able to use sever side scripting, but I will have access to my site's DNS management.