Preferred Source

In a route you can specify “preferred source” to tell the router when using that route itself to prefer to use that source IP rather then determining the source on its own. Is there an equivalent way to do this on Cisco? Since Mikrotik does not support any DS3 or T1 cards that are in production I have a Mikrotik talking to a Cisco and I need something like preferred source to hide the 10.0.0.2 address I use to route between Cisco and Mikrotik.

Matt