Yes, Quicktime had an MPEG2 codec too. But that requires some oomph on the Mac-side.
What's the raw material you want to encode? A modern mp4 container to Quicktime?
For ease of use, I'd use Quicktime Pro and use Cinepak as codec. I don't know if that is still supported on modern Quicktime versions, I seriously doubt it. I'm doing all my conversion on my Power Mac G4, so I'm not sure. You may want to setup a QEMU PPC Mac emulation as a bridge if you lack a real PPC Mac.
After a lot of testing, the conclusion is that Cinepak offers the best quality vs. file size on 68k Macs and it's what I encode all low-res (68k) movies on Cornica as well. Plays well on Macs with a 68030 or 68040. For Plus, SE etc. use Macflim as suggested.
Here's a small tutorial on Cornica about the settings I recommend to folks who want to upload movies:
http://www.cornica.org/how-to-convert-quicktime-video