No, because while it will generate Intel code for the JavaScript compiler source, that Intel code when it runs will be generating PowerPC code. Like I say, I haven't really made the changes for crosscompilation because it's only building for PPC, and I don't have any way of testing them. Some stuff I added is hardcoded to build PPC and the stuff that isn't, I haven't tested.
The former. It's not a trivial change.
I have to say this candidly: if you're on a legacy machine and you want continued support, you're going to be doing it yourself. I write TenFourFox because I have a need. It just happens to be a need a lot of other people have, so I make it available to them, but I write it first and foremost for me. So if you have a need for it, go for it -- working on Classilla taught me a lot about Mozilla code, which I leveraged working on TenFourFox. Dive in and learn. I wouldn't be as familiar with the source and the way the browser is constructed without getting my hands dirty. I'm certainly willing to give suggestions and tips.