Hi Bheki,
You can use the UI5 library with MII 12.2. You need to check the version of your netweaver server and which UI5 library it supports.
In the Blog by Sam, he is creating JSON Model as MII 14.0 supports JSON as output format.
Only difference would be that as MII 12.2 would return data from queries in XML so you either convert the data to JSON or use XML models.
Regards,
Rohit Negi.