You want to start by looking at the 'Support for bitcoin protocol handshaking' section of this page:
http://www.multichain.com/developers/peer-handshaking/#bitcoin
This examples how you need to set a bunch of parameters in params.dat in order to make your MultiChain blockchain compatible with a bitcoin wallet. You can still impose permissions on your blockchain in this case, but your wallet might not like the OP_DROP metadata in the permissions transactions. If you want to use MultiChain's native assets (as opposed to just the blockchain's native currency) you will also need to make further modifications.
I'm sorry we can't provide more precise step-by-step instructions at this stage.