Firstly you need to be in a co-op game and be on chapter 4 or 5.

When using the SK-1P and you're in the passenger seat you can see the words "/improbability drive...42" 3rd on the screen in the back when you're heading for any of the destinations. It's hard to see but you can make out the words.

Thanks to Adagio_Leopard for helping find this gem after 9 years since the games' release...

Screenshot from the passenger side:

Zoomed in screenshot: