Yes, it is possible to run IrfanView on Mac OS. Although, IrfanView wasn't designed for Mac computers there some ways to run it under Mac OS.
First of all, you need to install WineBottler on your Mac. It is a program that allows you to run Windows applications on Mac.
After running WineBottler, go to "Install Predefined Prefixes" section and select IrfanView from the list (yes, it's already there, fortunately). You will be prompted to specify the destination folder where you want IrfanView to be installed. The installation process is similar to the one that you perform on Windows. After the installation finishes, go to the folder that you have previously specified and run 'IrfanView.app'.
Given the fact that IrfanView is not a native-Mac application, it doesn't actually integrate into Mac OS. (Mouse gestures might now work).
On mac.informer.com, there are other alternatives to IrfanView. One of them, which I strongly recommend, is Xee. You could also try the well-known Gimp, as well as Seashore. Both are open-source applications that will allow you to view and edit your images.