I'm currently installing qt4-mac and it's taking forever to build. I've searched around and I've discovered that it's going to take anywhere from 2-5 hours to install.
Is there a way to interrupt this installation process and if so do I need to do some clean-up afterwards?
Have you tried using control+c?
Also, I'm not entirely sure about cleanup, but according to the MacPorts docs, the command sudo port -fp uninstall --follow-dependents [your port name here] should help (this page is about uninstalling MacPorts itself, but it's the same command). I'm not sure how MacPorts treats interrupted installations and if it treats "half-installed" items as uninstallable, but it's worth a try.