IIRC Bare multisig is not standard, but using OP_RETURN is. Using bare multisig for this will burn Bitcoin.

The basic idea is to break up your data into 65 byte chunks, which are the "public keys" as interpreted by Bitconi's scripting system. Then you just make the output in the multisig format,
where OP_X is the number of . You can only go up to OP_15.