It basically works the same way as the Flickr instructions, but instead of joining a group, just tag your Instagram photos #archidose (I'd link to the tag here, but Instagram only allows clicking on tags that through their app) and I'll dig through them as I consider what to post. It helps that a number of proactive Instagram users have already been using the #archidose tag.
To start, here is one of my photos, of SOM's One World Trade Center as seen from West Street:
To contribute your Flickr images for consideration, just:
:: Join and add photos to the archidose poolTo contribute your Instagram images for consideration, just:
:: Tag your photos #archidose