I want to distribute a combined work containing program X, plugin P and plugin Q. Plugin P has a proprietary license (which allows redistribution) and plugin Q is distributed under the GPL. X has a license which is compatible with both, such as LGPL.
Obviously, I'm not allowed to distribute this combined work under any license.
Can I distribute an installer script which installs X, P and Q on the user's computer when they run it? Is there any GPL violation happening here?
I may even include copies of X and P, or X and Q, inside the installer. The other component will be downloaded from the Internet so that I can claim the installer is not derived from it.