That's not an easy job, you'll need to change pedal assembly, you'll need an accelerator pedal position sensor, you'll need a corresponding throttle body to get it wired with the pedal position sensor, you'll need transmission, you'll need driveshaft, you'll need to replace your differential to match ratios with automatic transmission, you'll need new wiring harness (from an auto variant), you'll need to wire it all (gonna be a nightmare). You'll need auto shifter assembly and then after all this, it MIGHT work.
Regards.