Connect phone to pc, enable usb debugging and open adb. Type:
adb pull /system/framework/framework-res.apk framework-res.apk
That will pull your framework-res.apk to whatever folder is displaying in your command line.
Find the framework-res.apk on your hard drive, right click and open with 7zip.
Use png's here or create your own and dump into the appropriate folder within framework-res.apk.
When you are done editing the files open up adb and type the following command:
adb shell mount -o remount,rw -t yaffs2 /dev/block/mtdblock2 /system
adb push framework-res.apk /sdcard/framework-res.apk
adb shell dd if=/sdcard/framework-res.apk of=/system/framework/framework-res.apk
That will put the new framework-res.apk on your phone. It should automatically reboot (if not reboot it) and your changes should be applied!
When running the script above you can replace framework-res.apk with whatever you want. For example, Timescape.apk
Remember, it is CASE sensitive I made this problem many times)
If you would like to pull an entire folder put a slash at the end of the last word. For example, adb pull /system/etc /etc"/" (no " in actual script
Courtesy of corruptfate is the steps to modify the startupshow (post #207)
step 1: open adb shell
step 2: type "adb shell"
step 3: type "su"
step 4: type "mount -o remount,rw -t yaffs2 /dev/block/mtdblock4 /system"
step 5: type "mkdir system/etc/semc/startupshow"
step 6: exit and redo step 1 - 4
step 7: type "mkdir system/etc/semc/startupshow/default"
step 8: exit and open command prompt again, this time type "ddms"
step 9: look for the default folder in system > etc > semc > startupshow > default
step 10: push the images into that folder