How do you piggyback airport extreme wireless stations?
How do you piggyback an airport extreme wireless station with a time capsule wireless station?
If the word "piggyback" means that you want the AirPort Extreme to "extend" the wireless signal that is being provided by the Time Capsule......see this Apple Support Document.
http://support.apple.com/kb/HT4259
If it does not....please tell us what you are trying to accomplish.