Is there any way to program an Arduino MEGA 2560 with an Arduino Uno (or with MEGA 2560)?
If the Arduino MEGA 2560 R3 supports ICSP i don´t see a reason why it it shouldn´t work.
Arduino_ISP is using ICSP but you need a wire connection. If you want to do that remotely you need to add a wireless transfer module (Rfid e.g.) and transmit the .hex file wirelessly but you will need to alter Arduino_ISP to be able to receive .hex filed wireless and use a second processor on your board which receives the .hex and transmits it via ICSP to your Mega 2560.