To install PowerPC apps like FCS 2 you need Rosetta (not to be confused with Rosettastone!). If you have or can acquire a copy of Snow Leopard, you can extract Rosetta from it and you'll be good to go. I think there's also a workaround requiring a bit of a code hack but you'll have to google for it. I was lucky enough to buy a copy of Snow Leopard from Apple when they put it back on the market.
My specs: FCP 6.0.6, El Capitan, rMBP 15" i7 2.6 GHz, 16 GB RAM
Thank you. That's What I wound up doing.
I had a copy of Snow Leopard.
It was a little tougher than what you said because I'm on an iMac with no DVD drive, bit I made a disk image from my old PPC and then brought that over to the iMac and installed Rosetta.