No, you don't need to be rooted. You just need a file explorer installed(like Astro, File Expert, etc.) to go to the download folder and select the .apk file to install, aftet you download it of course.
None of them are working for me, im on the HD2 rooted with android CM7. All 4 of them say ""sorry! the application has stopped unexpectedly. please try again". Downloaded them and put them on the root of my sd2 and installed them through Astro. Not sure why they're not working.