Shorten Author name (3 letters) in In-text citation modification

Hi there, in our institute we use a slightly changed changed citation style from DIN 1505. I found several DIN 1505 citation styles using the 'get more styles' function. I was able to modify most things the way I want them, but I can't find a way to shorten the authors name to only the first three letters (how we cite). So text like Newmann, P.: How to be a badass, 2001 should be in text as follows: /New - 2001/. So far I am just able to get /Newmann - 2001/. Thanks for you help