Boot Camp x64 is unsupported on this model

I am in a panic mode and I need assistance. I have a mid-2007 iMac running Mountain Lion and I just attempted to install Windows 7 using Boot Camp. The Windows 7 installation went fine but I am unable to install Boot Camp and am therefore unable to get back to OSX. Here is what I have attempted so far:

1) Ran setup.exe from CD as admin. That is when I get the message that Boot Camp x64 is unsupported on this model

2) Copied the contents of the CD to a local Windows drive and ran from there. Same error.

3) Tried running setup.exe in compatibility mode. Same error.

4) Ran BootCamp64.msi and then BootCamp.msi from the command prompt running as administrator. I was able to install the drivers this way but the Boot Camp utility that would allow me to get back to OSX did not install.

5) I fried my Apple keyboard with the 'option' key on it and have been using a Microsoft keyboard for several months now. The instructions indicate that I would be able to select a startup disc if I were to hold down the 'option' key while restarting the computer. However, since I do not have an 'option' key on my Microsoft keyboard, I am unable to get back to OSX.

So, now my Mac is stuck in permanent Windows mode with no escape.

Any help would be greatly appreciated.

Thanks.