I have an 05' EU Roadster Pack. And this model has no steering wheel audio controls.
So I don't gain experience to control the Empeg remote.
What you will need is a converter to translate the signals from the Nissan steering wheel to the Sony stalk format.
And then of corse you need an tuner.
Myself I use also an PAC Audio Converter to connect the empeg to the factory Bose amplifers.
An important thing is to know that the empeg has low-level outputs and the factory amplifer has hi-level inputs.
Before I have bought an small amplifer to convert the signals I testet the sound quality witout any amplification.
The sound quality was not bad. It satisfy my requirements. One limitation is the the minor maximum loudness.
Here is link to service manual for the EU-model. There you can find a audio schematic.
And
here is a picture of my dashboard.
I hope I was a little help for you.
Andy