To get the download version of the game (or the patch for a retail copy) up and running on an offline machine:
Right click on the game in SDC, and choose Archive Application->Selected Application to pack it up without redownloading.
When the archive process finishes, you'll find the .sdc file(s) in C:\Program Files\Stardock\Stardock Central\BACKUP (this path is customizable in SDC's settings so it may vary). Copy the .sdc files along with the SDC installer to the portable media of your choice (CDR, DVDR, USB drive, etc).
On the other computer, install SDC, then double-click the .sdc archive files in explorer to unpack them.
If the other computer is not internet-connected, when you run the game you'll be prompted to activate. Enter the appropriate information and attempt to proceed; it will fail and offer you an option to activate by email. Copy the subject line and mail body it provides and get them back to the connected machine; email them off as directed, and follow the instructions in the reply to complete the activation process.
