ne's manual

4.9.13: LoadPrefs

accordingly.

If the optional filename argument is not specified, the file requester is opened, and you are prompted to select a file (you can inhibit the file requester opening by using the NoFileReq command; see NoFileReq). If you escape from the file requester, you can input the file name on the command line.

Note that a preferences file is just a macro containing option modifiers only. You can manually edit a preferences file for special purposes, such as filtering out specific settings. See Hints and Tricks.