This can be done with SDMerge.

The purpose of SDMergE400 mod is to
get more space for user data by means
of removing the unnecessary 1GB
internal SDCARD. Technicaly it is done
in 4 steps:

Step 1 - Update recovery to use
custtom one that support expert
partitioning
Step 2 - Re-partition the internal
storage and create filesystems
Step 3 - Install fresh Cyanogenmod 9
nightly
Step 4 - Install SDMergE400 modifier
for CM9 nightly.


Main features:
1. Extended data partition 1.15 GB
2. Battery / power up fix
3. USB Mass Storage fix
4. ICS device encryption fix
5. Ability to set up Suxsem 1GHz /
tun / swap kernel after Step4.


How to install (for the first time - no
previous SDMergE400 mod installed):
1. Download archive with all parts from
the download link below and unpack
its contents to External SD card.
Download the latest CM nightly to your
external SD card too. Make sure the
phone is fully charged!
2. Ensure you have CWM 5.8.4.5
recovery installed.
3. Plug off the charger and reboot into
recovery
4. Apply SDMergE400_Step1.zip from
sdcard. The phone will reboot on
success prompting you a new recovery.
5. Apply SDMergE400_Step2.zip from
sdcard. The phone will reboot on
success prompting you an old recovery
for step3 and step4 completion.
6. Apply CM9 install and after it
completes, apply
SDMergE400_Step4.zip from the
sdcard.
7. Reboot and cross your fingers - after
2-3 minutes max you will see the SIM
card PIN lock screen.
How to apply newer CM nightlies:
1. Copy CM9 nightly to external card
2. Apply from CWM recovery
3. Apply SDMergE400-Step4.zip from
external card
4. Reboot normal

All you user data should remain intact.

DOWNLOAD LINK: http://sendfile.su/787227
the first blue button is download, 20mb.

How to revert the mod:
1. Reflash KDZ to stock 2.3.6 kernel.


Credits:
Thanks go to SWAGGZO NL
080three9279411