It's really not that easy. This was just a one-off side project of mine a few years ago. It wasn't part of the official project or source. While i got close, the browser was still partially broken (bookmarks broken, downloads window broken, having to manually add extensions / themes, packaging was broken, and a few other quirks). I ended up manually adding in some of the old TFF38 patches and some other hacks to get what i got posted here. Sadly the HDD in that G5 bit the dust taking everything on it to the grave. I never bothered attempting it again after that as it took months to get that far, and it's code base wasn't any newer than TFF's. So rendering the modern web wasn't going to happen with it, and i saw no need to pursue it again.
Having said all that, Riccardo does have mainline AF building on 10.5 intel now, but it crashes when drawing the UI elements. All i can say is keep an eye on it, and maybe it'll build out of the box on PPC OS X in another year or 2.
Cheers