I'm doing it on my Cefiro but it's the same as the S13.
Your just looks fucked!
But you'll be glad after your finished! I know I would be after seeing all that!
Here are the FSM's JDM and US versions
you will need to look at the S14 one for the Digital diagram.
It's the same as the S13 but not sure about the wire color codes I used a A31 diagram I found to rewire my set up. but placement was the same on the harness.
Manuals > JDM and European Cars > S14 Silvia - Zenki (SR20DET) - Nissan 240SX Performance Tuning
Here is a youtube video also on the DCC install if it helps
S13 Digital Climate Control Conversion - Part 1 - YouTube
If you were local I'd give you a hand... good luck!
PS, Remember to heatshrink and soder everything!
You might as well spend the extra time to do everything the right way now than have electrical tape everywhere and have to do it again later.