Answer
ESRI does not document changes made to the registry during installation. The registry keys are created when the DLLs are self-registered.
If desired, it is possible to produce a list of the changes:
A. Export the registry before installing.
B. Install the software.
C. Export the registry after the installation.
D. Use a Kdiff tool to view the differences in the registry that were created before, then after the installation.