sure. In the SA use the media master control (the VCR-looking thing) to do this. On the drop down arrow there's the option to 'paste from file'. Just select the greeting you want to replace, select paste from file and browse to the WAV file you want.
Are you getting this error “Installer User Interface Mode Not Supported. The installer cannot run in this UI mode. To specify the interface mode, use the -i command-line option, followed by the UI mode identifier. The value UI mode identifiers...
The below trick might come handy when you have to add a new node to a cluster but you don't have or is unsure of the security password for the publisher. This procedure has been around for ages.
1) Login into the CLI of the Publisher.