The Mac version of ParcPlace VisualWorks 2.5 is made up of 5 disks in 
a self-installing format. 
The names of the files are:

Installer
Installer.2
Installer.3
Installer.4
Installer.5

These files can be copied anywhere for distribution but they must be
transferred to a Macintosh using a macbinary protocal. Most Mac ftp clients
offer this. Once transferred to the Macintosh, place all the files in a
single folder. Double-click the Installer icon and follow the directions.