Not sure if it works with breast milk, but with formula, some people introduce cows milk by making up bottles/cup with part formula part cows milk together and gradually increase the amount of cows milk to get dc used to the taste. I don't see any reason why it shouldn't work with breast milk but there may be someone with more experience of this who can tell you for sure. Have you tried heating it up before you give it to her?
You can do a gradual mix when introducing cow's milk. Be sure she is eating a decent diet however before switching. If she isn't taking in much in the way of solids just yet, might be better to switch to formula for awhile to be sure she is getting the level of nutrients she still needs.