Do you want to do MIRO only for service entry sheet??
I suggest don't anything in MIRO t-code..
Consult with your ABAP team, they will make a new program from copy the program SAPLMR1M.
And tell them to remove the all option for Reference without Service Entry Sheet..
Then assign the program to a new t-code like as ZMIRO..
Then you can give the authorization only for ZMIRO to a user...
Then he will only able to see the service entry sheet reference...