FWIW, I needed to do this today, and fortunately have access to an old laptop that i was not using for anything else. It allowed me to do this:
1. Install the old command center app on the laptop.
2. Install Sonar Artist, just the main app and the "Artist " tools which i could pick from the list of things under the main Sonar Artist product.
That installed all the session drummer 3 stuff into a Session Drummer 3 folder under VSTPlugins.
So i just zipped that entire folder and moved it over to my existing working Bandlab Sonar machine. I unzipped the files into the same vstplugins folder on the main machine. I also exported the HKLM registry hive for Session Drummer 3 which had the paths for the content (see below) and added those reg entries to the main machine.
Everything worked as expected. When i next launched Bandlab Sonar, it did a VST scan and picked up the new Session Drummer 3 VST entry.
Registry info:
Windows Registry Editor Version 5.00
[HKEY_LOCAL_MACHINE\SOFTWARE\Cakewalk Music Software\SessionDrummer3]
"Contents Folder"="C:\\Program Files\\Cakewalk\\VstPlugins\\Session Drummer 3"
"Resources Folder"="C:\\Program Files\\Cakewalk\\VstPlugins\\Session Drummer 3\\Resources"
"Documentation Folder"="C:\\Program Files\\Cakewalk\\VstPlugins\\Session Drummer 3\\Documentation"