You just need to install the Design 3D CX plug-ins into your new Photoshop CS5 or CS5.x.
To do this, first find the plug-in installer. For Design 3D CX 7 on the Mac OS, the installers are located here:
(Your user account)/Library/Application Support/Corastar Inc./Strata Design 3D CX 7/Optional Installers. The installer is named "Ps Plug-ins for D3D CX 7."
If you're running Windows, or Design 3D CX v6 or earlier, the Optional Installers folder is located in the Design 3D CX application folder.
Open and run the installer. It will ask you to locate the Photoshop plug-ins folder. Select your Photoshop plug-ins folder, and install the plug-ins there. You will need to restart Photoshop to see the plug-ins.