HI Swaroop,
Basically as I stated in my original post we were looking for some kind of tool or application through which I can migrate MII projects from MII 12.1 server to MII 15.1 server, the migration tool as suggested by you helps only when the source system is MII 11.5.
Never mind, I ended up developing small .Net application which uploads MII projects as zip files to ease the process.
Many thanks
Rupesh