The psi is going to depend on the temp and the carbonation level that you want. There are many charts out there that list "proper" carbonation levels for various styles, for example from brewer's friend:
British Style Ales 1.5 - 2.0 volumes
Belgian Ales 1.9 - 2.4 volumes
American Ales and Lager 2.2 - 2.7 volumes
Fruit Lambic 3.0 - 4.5 volumes
Porter, Stout 1.7 - 2.3 volumes
European Lagers 2.2 - 2.7 volumes
Lambic 2.4 - 2.8 volumes
German Wheat Beer 3.3 - 4.5 volumes
Once you have selected your desired carbonation level use
this chart to find the proper psi for your temperature.
Edit: note that if you're really going to carb your hefe "to style", you'll likely need pretty long lines. Check out all the threads on balancing your system. I tend to keep it pretty simple and carb all my beers to about 2.5 except those I'm going to serve on beer gas, which get about 1.5 vols.