If u want the unsecured way
First of all; I am in no way responsible for whatever you might do to your phone if you choose to follow this tutorial. You might render it completely unsusable for all I know. And that's bad! But not my problem.
First of all you'll need the
FAR Manager program. Download and install version 1.70.
Edit: Then you'll need the
latest SE Flash Plugin for FAR Manager. Unzip the content to the ..\Program Files\Far\Plugins\ folder.
The "Increasing your SMS storage space" tip
This is the file you need to change in order to increase the SMS storage space:

Move to /ifs/settings/messaging and go to the file: pref_store.txt press F4 to edit.
edit the path /smsdata to read:

/tpa and press F2 to save and F10 to quit the editor.
You might also have to make some of the following folders:
/tpa/messaging
/tpa/messaging/sms
/tpa/messaging/sms/msg
/tpa/messaging/sms/FFFFFFFFFFFFFFFFFFFF
/tpa/messaging/sms/FFFFFFFFFFFFFFFFFFFF/pending
/tpa/messaging/sms/FFFFFFFFFFFFFFFFFFFF/sm
/tpa/messaging/sms/FFFFFFFFFFFFFFFFFFFF/sr
/tpa/system/messaging/sms
To make folders just move to the folder where you want the sub-folder and press F7 and type the folder name in the box.
Remember to move to the root folder and answer "yes" to end the CSFSloader.
Disconnect your phone and wait a few seconds before turning it on.