I saw people do this on YouTube, at least in the console version. They were able to lift items up and carry them around without putting them into their inventory. It was mainly used to carry items to a safe spot for stealing.

Z/Y key, depending on keyboard layout. Press again for release. Physical obstacles may break hold on item.

Edit: Quite clumsy method imo. Some people are actually using this to decorate their player homes. I shudder to think...

I use this to decorate my house

http://www.gamesas.com/topic/1516543-home-sweet-home-home-base-ideas-and-discussion/