OK, I got impatient and just spent about three hours manually installing Cupcake via some great videos on YouTube. It was a little hairy at times because I did not follow directions to the letter, but now I have it and IT IS FANTASTIC.
So you know, there are different versions of Cupcake floating around out there. The one you want is in the link below. I am in the U. S. and I did not want the European Magic cupcake version that is out there.
Basically, if you want to do this manually, because you can't get it from T-Mo where you are or whatever:
1. You have to jailbreak your G1. What this means is that you have to wipe your phone (reformat in a sense) and install the original OS that came on the phone in Sept. 2008. It was RC29
You have to do this because the Sept. 2008 OS had a security hole (that has since been plugged by Android). It is this hole that allows one to mod the G1.
2. After you jail break or "root" the phone, you then install RC33 which was the update to RC29, the original OS.
3. After that you install Cupcake 1.5
It's all fairly easy, but it's time consuming to make sure you do everything correctly.
There is this one YouTube member who has the best tutorials (for both rooting and jail breaking the G1 AND also installing cupcake). Also he has links for every file you need to do everything.
Here are his jail breaking videos:
Part 2:
Here is his cupcake install video.
WARNING: AnthonyMoreno24 has two cupcake videos, the first was for the initial cupcake.
He later determined the JFv1.5 (Jesus Freke version 1.5) cupcake version was better, so he made a tutorial for that one. Which is linked above.
You only need to follow the instructions for the one video and install, not the earlier one.
Note: The hardest part is entering the key commands correctly. Make sure to read each videos comment sections as there are some tips in there too. For example, he says to rename certain files "update" That did not work for me. I had to name them "update.zip" Not sure why that is, but you can see that variation in naming in the comments section.
Bonus: In the cupcake video he also tells you to update the "radio" part of the OS. The radio update will improve the cell phone portion of the G1. So make sure to do that.