When you run UIEOrchestratorStub.exe it executes UIEOrchestrator.exe program located here:

%SystemRoot%\uus\<architecture>\UIEOrchestrator.exe

So, changing the SystemRoot environment variable to point to your chosen path will lead to execution by proxy.

On a 64-bit Windows 11 26H2, we can try this:

set systemroot=c:\test
UIEOrchestratorStub.exe

which will launch:

c:\test\uus\amd64\UIEOrchestrator.exe