You can run a custom executable from the Customization/Preferences tab of the launcher:
Enter the full pathname to the custom executable in the Custom Ansys
Executable field. Do not include the -custom argument.
When run from the command prompt, if no path is specified after the
-custom argument, the ansys242
script searches the current working directory for the custom Mechanical APDL executable
(ansyscust.e by default on Linux or
ansys.exe on Windows). If the custom Mechanical APDL executable resides in a
separate directory (or has a name other than ansyscust.e on
Linux), you can specify a different path and filename after the
-custom argument.
Caution: If you are running on a Windows system and you create a custom Mechanical APDL executable, it must be named ansys.exe. This requirement is due to shared library usage.
On Linux, you can also run your custom executable via command line.
ansys242 -custom /pathname/ansyscust.e