Ok, here's the steps for changing the Downloads icon to Android 4.0 and fixing up the look of the Settings sections so they all have the right icons. Check back one page to see what I mean. To both of the following, you'll need the android sdk manager and tools with everything up to date and "SAMSUNG USB Driver for Mobile Phones" downloaded from the SDK manager. (Let me know if you can't find that, i'll help.) Back up your system, as always, then delete "DownloadProviderUI.apk" from your phone using a root file explorer. Reboot your phone. Continue on to the following steps:
Download icon:
When we finish, it will look like this:
Step 1: Plug in your phone and turn on USB debugging by going to Settings > Developer options > USB debugging. Your Nexus S 4G must be running this ROM. I only tried this on the latest 3.6 release from yesterday.
Step 2: Browse to the "tools" folder in the program files. On Windows, go to (My) Computer > double clock the "C:" drive, go to Program Files, Android, android-sdk, tools, then finally double click ddms.bat. If that doesn't open up, right click it and click "Run as Administrator".
Step 3: Let it open up and when it does, you'll see a string of letters in numbers with a tiny image of a phone to the left of it. If you don't see this, make sure USB debugging is on. Click that, then click the Device menu at the top and choose File Explorer.
Step 4: Download the following file and put it on your desktop.
http://dl.dropbox.com/u/15668564/DownloadProviderUi.apk
Step 5: Go to system then app
Step 6: Click on any .apk in that folder, then choose the icon at the top left with a small phone with an arrow on it facing the right. Click it, then find the apk we downloaded in Step 4. Double click it click open if it doesn't automatically. "DownloadProviderUI.apk" will be added to the list of apks. Then, click that apk and choose the same icon we chose before, the one with the arrow facing the right.
Step 7: Go to your app drawer and check to see if Downloads has been added to it. Then icon should be the new downloads icon as see above. If not, reboot your phone, then check.
Changing the Settings app as see on the previous page:
Follow the same steps as above, including the steps in the paragraph at the top of this post first.
When you get to step 4, download the following file instead of the Downloads apk.
http://dl.dropbox.com/u/15668564/Settings.apk
Follow the same exact steps after step 4, except you'll be dealing with the Settings apk from above, instead of the Downloads apk.
If you need any help, please let me know via PM or here.
Post letting me know how it worked out for you.
PS: I tried just deleting the original files then trying to install them by copying to system/app on my phone and it didn't work which is why I tried this.