If the installation was done through .msi file then some of the additional components of PSE does not use to get install on the user machines and hence the .msi file installation was locked out in PSE 8.
The error you are seeing is because you are trying to install PSE through Adobe Photoshop Elements 8.msi file. Please try to install PSE through Setup.exe and then the installation will run fine.
In either case, for silent deployment on multiple machines, you should contact Adobe support team which is designed specifically for the enterprise customers to assist them in deployment related issues. Also, you need to get volume serial number in this scenario.
Also, Adobe strongly recommends customers not to directly edit the installer files using some tools like Orca. In case you need any customizations or support, feel free to contact the support team for enterprise through the link I shared below or by directly calling the support.
Thank you for the reply, Ankush.
The idea of installing from the .msi file is to make the installation universal. If we create a custom .mst file to run with the "Adobe Photoshop Elements 8.0.msi" file, it can be configured to automatically use the language selection previously configured in the Windows operating system. This makes it much easier to develope for our sites around the globe.
I will try and contact the Support Team you have suggested.