Check these two articles:
http://support.apple.com/kb/HT4649
I checked the above myself after the failed attempt to create a recovery HD; from what I've gathered (and I've not had the time to test this myself), I'd need to boot into my clone, from there boot into (internet) recovery and it may create a (local) recovery partition for me:
http://support.apple.com/kb/HT4718
FWIW: my external clone was created using CarbonCopyCloner and it did successfully create a recovery on a Lion volume; however, it may not be completely compatible with ML yet because it messes up the system if you try having it create a recovery partition on an ML volume. So I chose not to have it do that and just cloned the OS - hence no recovery HD. As far as I know, there is no other software that can create/copy a hidden partition (except CCC) as of yet.
The perfect solution: I want install media!