You can download and install iris. (alpha) from 1Mobile Market, which is a legitimate alternate app store. Make sure to allow apps from outside of the Play Store by going to Settings -> Security -> Device Administration, and check "Unknown Sources".
Go to to download and install their app store app (ironically, the app is available on the Google Play Store, but it's marked as not compatible with the N7!). They only have free apps, including those that are listed as incompatible with the N7 on Google Play. Unlike the Play Store, 1Mobile let's you download these apps. I've downloaded and used CNN, USA Today, American Express, and Discover Card without a problem. I just checked and they have iris. (alpha) available. Of course, that doesn't mean it will actually work, but at least you can install it and try it. This is much safer than getting the apk from some shady website.
The most recent version of 1Mobile is kind of annoying with a Halloween theme, so hopefully they'll update again soon. Otherwise it's a pretty good app store application.
Other reputable app stores I use are Amazon and SlideME Market, though I checked SlideME and it doesn't have iris.