I just did this tonight. I did not wire into any fuses though. As you look at the radio, do you see some connector plugs on the driver side of the radio just plugged into the plastic, not plugged into anything? I grabbed one of those, found which one worked on the key, then cut/spliced that into the red wire of the deck. Let me know if I need to clarify any while itís fresh on my mind. It should be your red wire as the keyed wire. On the connector it will have the yellow constant wire mating with the gray/striped wire from factory side but no keyed red wire. That red wire needs to go to the red wire I was referring to that is keyed.
I hope this helps some, let me know..
2009 Ram 2500 SXT 6.7 QCLB