Not so easy solution on this one for me, but try this:
(Also the australian way of approaching the same
thing is just different enough to throw me off track
Go to the control panel to Programs and Features and
choose Uninstall/Change for Revit 2012 to modify, and
then choose to Add or Remove Features, then choose
the content you need installed. (Don't know if that will
do it for you though).
I knew they changed the content loader for 2012 but I
never paid much attention to it because I just let it
download the content and then I copied it all to a
secondary drive and I will always have it.
Also keep in mind that the 2011 content is virtually the
same as 2012, in case you come across that stuff too.