I'll just repost my reply to the poster asking about converting their Indian commercial.
There is no conversion of licences at the commercial level in FAA land. 61.123 lists the basic requirements and the following sections list the other requirements. You must hold a FAA private certificate. A private certificate issued under 61.75 is OK. Then you must pass the commercial knowledge test, receive the required flight training, have your logbook endorsed stating you are ready for the checkride and pass the checkride. Same four steps for the IR.
And of course you have to jump throught the TSA hoops and get a medical.