Please try this using adb:
* mount the system partition read/write
adb shell mount -o rw,remount -t ext2 /dev/block/mmcblk0p5 /system
* remove your gmail apps:
adb shell rm /system/app/Gmail.apk
adb shell rm /system/app/GmailProvider.apk
* download the apps from here
* push them to the device
adb push Gmail.apk /system/app
adb push GmailProvider.apk /system/app
* mount the system partition read-only
mount -o r,remount -t ext2 /dev/block/mmcblk0p5 /system
* reboot the device