Decide whether Cubase or Acid will be the host program, and open the program. Choose any desired project.
Open a ReWire channel for the programs to communicate. If Cubase is the host, click the "Devices" menu at the top of the screen, and on the "Sony Acid" ReWire device. Enable channels for Acid by clicking the blue button to the left of the channel name at the pop-up menu. If Sony Acid is the host, click on "View" at the top of the screen and select "Plug-in Manager." Click "Cubase" from the menu and right-click a listed output. Select "Insert ReWire Device Bus."
Open the program that is to be the slave to sync it up with the host. The two programs will now work together.