There is no new installer for LSL7. What they were refering to was probably The intaller for the 1st two GK games. There is small utility that will show the hidden setup problem that the Windows installer has:
but you would be better off installing the DOS version and running it in DOSBox:
or with VDMSound:
I don’t know about QfG5, but, SQ6 and any other of the SCI games can be run fully from the hard drive. You just need to copy all of the resource files to your hard drive and edit your configuration file to point to the new location of these files, instead of the CD.