How do I reinstall CS5.5 if my iMac won't recognise my discs?

I had the hard drive on my iMac replaced recently.

Although I backed up all my InDesign files, I did not back up my CS5 applications as I have the oringal discs

When I tried re installing CS5.5 my iMac did not recognise the discs at all and then spat them out after a few seconds with a whirring noise coming from what must've been the DVD drive I guess.

I phoned Adobe who said there is a known issue with reinstalling (CS5.5) discs.

They also told me there are no CS5.5 downloads available, which was interesting as I found a CS5 forum which had a link to download CS5. I tried this link and it didn't work.

The Adobe help person suggested I stick my CS5 discs onto another iMac and then copy these CS5 files onto this iMac's desktop. From this desktop, I then copied my CS5 onto an external hard drive. I then plugged this external hard drive back onto my iMac (with the replacement hard drive) and copied all these CS5.5 files back onto my desktop. I then opened the install file and the installation process started working fine until I got a message saying,' Please insert Disk CS5_5 Mstr Coll 2 to continue'.

And now I'm truly stuck as my iMac won't accept, or read, my CS5 discs. Any ideas on how to sort this out?

BTW - I also tried setting up a new user profile. That didn't work