This might help...
After last trip to SP in Nov. 2009, I decided to bring back donations for the SP Library on my return trip in Aug. 2010. So I contacted Iracela Acosta, Sr. Librarian at the Library @ sptlibrary@hotmail.com.
Once I provide her with a list of what I am planning to bring, she will assist with a customs-exempt letter.
I am planning to bring books, art supplies, school supplies (and HOPEFULLY a laptop or two) to donate to the library.
I would think that the school would be able to provide you with something similar.
Or try contacting...
http://www.customs.gov.bz/exemptions.html