change 110v to 240 v for a MF cd plaer

Depends on what easy means to you. The change is about a power supply differencewhich might be as simple as a on board switch that is not accessible from the outside that will do it for you. I don't know what the design is but maybe the manufacturer put a switch in for this. If not then you would need to find a transformer that has the same output voltage (or pretty close) as the one in there now but with a 240V input. It wouild need to be pretty close in size too. That might be hard to come by.

The easiest option would probably be to buy a transformer from some where like an electronics store (Radio Shack in the U.S.) that does it for you externally. Then you just plug it in and be done.