Manually edit apple mobileconfig

Question

I am trying to create mobileconfig files manually. I created one mobileconfig file with the apple configurator. this file is the source for all of the following files.

Now my problem is, I do not know how to manually add / replace the pkcs12 (pfx) file to the mobileconfig file. The mobileconfig source file contains a private certificate with a key / password.

Now I want to replace this certificate with another private one.

under the tag "payloadcontent" is a tag named "data". this tag stores the certificate as base64 encoded in the .mobileconfig file, this is written in the Apple payload content document. when I export the pkcs12 certificate with openssl to pem (base64), I get other data that is displayed in the .mobileconfig file.

so my questions is 1. payloadcontent / data stores pkcs12 (pfx), right? 2. Why are the data displayed in the .mobileconfig file not displayed in the conversion file (base64)? 3. How can I manually add a private key certificate to the mobileconfig file? 4. Do I even need a secret key or does a certificate for authentication on a wireless LAN just work?

thanks:)