Recover purchased Snow Leopard OSX

I purchased a 5 user license of OSX snow leopard CD from the Apple online when I was using OS X Tiger. Then I have upgraded my MAC Pro from snow leopard to Lion. The HDD was dead and I built my MacPro from OSX Tiger CD but I lost my OSX snow leopard CD. It is not allowed to upgrade from OSX Tiger to Lion directly. I'd like to know how to download my purchased snow leopard or how I upgrade from Tiger to Lion. Tiger cannot run time machine so I'm not able to restore the backup from my Time Capsule. Please advise. Thanks