There are basically two modes of entries into M.E. programs of BITS.
1) Through GATE, at least 85% in GATE along with good AIR is required for it, then you have to fill up the form for it, and appear for little written test,if you remain in merit list then admission will be provided,if required interview will also be conducted.
2) Through its own Online entrance.BITS also provide admission to M.E. through its own entrance test,registration for which has been started, the last date for applying is 31 may.So kindly check out its official website- HD Admissions
But only the students who had persued BE from BITS are only eligible for it.If you have any doubt please visit this page- HD Admissions