Since my school won't let me install an English version of PPT on my computer, I have to use OpenOffice. And after about 3 hours of googling and trying to get more than the two default backgrounds to work on it, I've still had no success.
If you have the Korean version of it, then it's pretty simple to add the English language onto it.
1) Go to isohunt.com or piratebay.org and download the SAME office version as your work computer. (Use MuTorrent to get the program)
NOTE: As you will be using the serial number your school uses, you are not actually stealing the program. You are just getting the English files.
2) Run the installation and choose "add or remove features"
3) Choose to install English
4) Go to Start>Programs>Microsoft Office>Microsoft Office 도구
5) Choose the one with the world and the A
6) Go to 일반 and change from Korean to English
That should do the trick. When you give up the computer you can change it back following the same steps.
*NOTE you will have to restart office to see the changes.