Rosetta, which was licensed by Apple to run PowerPC applications (after the switch to Intel CPU's) is no longer available to be run in Lion.
Your best solution is to upgrade Final Cut Studio 2 to a version that is native for Intel and will run in Lion.
To install software from a CD/DVD, you need to purchase the external USB DVD drive from Apple, or use CD/DVD Sharing of the drive from a networked computer.
If you are unable or unwilling to upgrade your copy of Final Cut, you could install Snow Leopard (and Rosetta) into Parallels 7 in Lion (these steps will require a DVD drive to access your copy of Snow Leopard Install DVD:
In a word, Rosetta is completely incompatible with OS X Lion and cannot be installed. You must either upgrade Final Cut Studio to a Lion compatible version, or you must reinstall Snow Leopard to get PPC support. You cannot use that application with Lion.
Hope this helps