Need settings for H.264 to AVCHD on DVD

Question

I'm trying to use Compressor 3.5.2 to encode a movie to H.264 for Blu-ray, which I will then feed to Toast for burning onto a DVD. The only settings I see in Compressor for that use bitrates that are much too high for the red laser DVD technology, so I need to knock the max and average down to 17 and 15 Mbps respectively.
Hoping to just tweak the defaults, I saved the "H.264 for Blu-ray" settings and can see and edit the .setting file, but if I touch it at all with TextEdit or TextWrangler, it no longer loads when Compressor starts and it's not available.
Can I get there from here?

Answer 1

Let me first just reiterate that my problem with Compressor is no doubt because I'm trying to use it in an unsupported installation on my PowerPC-based Mac. It appears to work fine in every other respect, but the Blu-ray file formats seem to not install or are otherwise invisible. My gut tells me the H.264 encoder is not Intel-only, but I can't interface with it. If there are other PPC users here, I'd love to hear if any can use the blu-ray features.
My process now is to edit my HDV camera video, sometimes adding photos, then export from iMovie (or FCP, but usually iMovie) via Quicktime as AIC video and PCM audio. My captured camera video files are ~100 Mbps. The export from iMovie to AIC produces a large file but is fairly speedy and avoids multiple compression steps later on. The large resulting AIC file can be dropped directly into Toast and emerge a couple days later as an H.264 video file (.264 extension, I believe a transport stream?) plus an ac3 audio file. Toast puts these intermediate files in it's Roxio Converted Items folder and will go ahead and multiplex these and put them onto AVCHD for playing on a BD player. It deletes the files if you quit the program or you're not careful, but you can rescue the encoded files at the intermediate step if, for instance, you want to replace the .ac3 with a surround mix you've prepared with Compressor. If you feed the intermediate .264 file back into Toast, this will not trigger a re-encoding and it will go ahead with multiplexing and burning.
In Toast you can tweak the average and max bitrates and the codec, AVC or MPEG-2, when encoding for AVCHD. Since AVCHD is limited by the red laser to ~18 Mbps, I've set Toast to encode to AVC at bitrates just below the limit. This should give the highest fidelity possible, and an overall compression from my source material of ~7X. In fact I did some testing and found that this produced a better image than sticking with Toast's default bitrates which were much lower (maybe 20X? overall compression), or with the MPEG-2 codec. Of course encoding to AVC takes longer than MPEG-2, but they're both slow.
So if this all works in Toast, why am I bothering with Compressor? Two main reasons:
1) I was hopeful that Compressor might be faster and/or better at encoding. If anyone here can address the speed versus quality issue for these two encoders, I'd appreciate hearing about it.
2) Toast can be flaky, for example sometimes hanging at the dreaded error -18771 after a day of encoding.
3) A third but minor reason is the availability of templates in Compressor I may like more than the Toast templates.