It appears you can’t launch an AppV environment around an application with the /appvve switch as Microsoft automatically strips the /appvve switch OR because icast.exe freaks out.
I have found an alternative method though:
powershell.exe -command "&{$AppVName = Get-AppvClientPackage *APPNAME* ; Start-AppvVirtualProcess -AppvClientObject $AppVName cmd.exe}
This will launch a cmd.exe window in the virtual environment in citrix with the passed .exe (cmd.exe in this example).
Dan mentioned another, less character way:
Start-AppvVirtualProcess -AppvClientObject (Get-AppvClientPackage *APPNAME*) cmd.ex