Anything is possible if you have the skills and money.
If your asking will it simply drop straight in then the answer is no, not only is the gearbox massive but there are loads of other complications to go with it ie hydraulic clutch arrangement, custom driveshafts, custom mounts etc....
Andy is running a F4R/F4RT hybrid engine with a JC5 gearbox
Is this a new megane, RS250 that has fallen off the trailer?