Here's some service manual docs on the temp display retrofit:
http://www.w124performance.com/docs/mb/W124/LCD_temp_testing.pdf
(0.7MB PDF)
http://www.w124performance.com/docs/mb/W124/LCD_temp_install.pdf
(2.2MB PDF)
That should answer your questions.
About the climate control pods, here's a link to an extensive thread with photos, in case you hadn't seen it:
http://www.peachparts.com/shopforum/showthread.php?t=35373
