Apologise first if I misunderstood anything.

But doesn't Chameleon bootloader already provide boot options??

This is how I see it (doesn't matter which OS to install first):

Let's say you want to install mac os first.

Bios settings: usually people have put AHCI up.
1. install mac os on hard drive (A)
2. Bios setting: Put back to Enhance mode. And boot priorities to DVD rom, boot from hard drive (B)...
3. place windows dvd into dvd rom and install to hard drive (B).
4. once installed -> Bios -> AHCI up, boot priorities: boot from HD (A)
5. Chameleon can see all available OS.

Pretty straight forward isn't it? Noob like me can also do it