Convert a ceiling fan controlled by two switches to a remote control
You'd need to replace the switch with a remote controlled switch. Since you currently have two outputs, you'd need to find one that has two outputs - I believe they sell one which has a button for the fan and another for the light. Regardless, they'd still have to be separate.

Also, getting this to work would require no modification to the fan itself or the wiring at it. Everything would be changed at the switches.

If you can't find a remote switch module that allows two outputs, then you'd have to leave one currently as is and only control the other.