Programming an MD5

I received my first MD5 and am trying to flash it on the bench. There is no Ethernet hookup so I'm using a G12. It is taking forever and I'm only getting a couple percent done before the MD5 goes blank (after around 10 mins) and seemingly stops. My questions are, what is the fastest connection to flash a system with the MD5? If its CANbus, what is the hardware/ how do I wire it into the system. If its Ethernet, how do I wire that into the system. I have also tried to create a program utilizing an MD4 and MD5 to utilize the Ethernet and the program wont recognize the MD5. I heard the G12s are fast but there is no way it will work as the main programming connection considering the experience Ive had with them.