When you right-click on a Xilinx device part in an SVF chain, you have the option of creating and associating a Configuration Memory device to it.
Figure 1. Adding a Configuration Memory Device
This opens up the Add Configuration Memory Device dialog box as shown below.
Figure 2. Add Configuration Memory Device Dialog Box
Select the appropriate memory device and click OK. The device is associated with the Xilinx device and appears in the SVF device chain as shown below.
Figure 3. Configuration Memory Device in SVF Chain