I know this sounds a bit old, because I've only figured how to do this just TODAY! :D
I was looking around to make my own carrier image for my boring iPod Touch, but I think I kept hitting the wrong keywords. And it always brings me to wrong places. So one day, I brace myself to ask someone (and hopefully he's a nice guy!) to figure it out.
Then one day he replied! I was overjoyed. Hahaha... Didn't really expect some complete stranger to help me out. I was so helpless.
Anyway, since I figured it out, I'm going to share with you how you could do it. (Full complete steps)
What are the things I'll need?
You'll need a PNG-8 image (don't worry if you don't understand), and it's maximum height is 20px for it to look good.
Next, you'll need something that you can access your iPod Touch's internal system. For me, I'm using the trusty iphonebrowser. Use google, I'm sure you can find it easily.
So what do I do? (Finding the correct file)
You'll need to search for the original file. If you don't want to lose it, rename it so that you can replace it if you don't want to use it anymore.
Step 1: Open iphonebrowser application
Step 2: Click on Goto Location -> Springboard Images and Settings
Step 3: Rename Default_CARRIER_IPOD.png into Default_CARRIER_IPOD.png.bk. This is necessary if you want to revert back to the original iPod carrier. Do the same for FSO_CARRIER_IPOD.png.
Step 4: Drag and drop your images (or you can use mine as a sample) into this same box (where you saw the files). Make sure the filenames are correct. You'll need Default_CARRIER_IPOD.png and FSO_CARRIER_IPOD.png as the filenames.
Step 5: Restart springboard by using Summerboard. Or killboard. Or you can use Erica Utilities. Any method you use, all you need to do is restart the springboard to take effect. Alternatively, you can simply reboot your iPod Touch.
[Gee Theme courtesy of RupertGee. Get your copy here.]
I need help! I'm a n00b13!1!111!!11
Well, you can always ask me. Or you can read the original write up. Either way, I hope to be of assistance to you.