You will need to be rooted to do this but once you are its easy and there are a couple of ways to do it. There is a font changer app that you can install which has a selection in it. Just a case of selecting the one you want and then rebooting for it to work.
Also you can download it as a zip file and install from recovery. Once you reboot it is permanently on your phone until you install another.
Good thread here that explains it all
xda-developers - View Single Post - [SOLVED] Changing fonts in Android?