Hi, I see you joined the forum to ask your question... Welcome
What a wonderful way to use school project proceeds...
Kiva takes online donations through PayPal... so you would need an account or credit card for that.
http://www.kiva.org/app.php?page=basket&action=donate other than that, you can send money directly to their office...
Kiva Microfunds
3180 18th Street, Suite 201
San Francisco, CA
94110 USA
But I think it would probably best to send them an email to the
contactus@kiva.org and get an answer from 'she/he who really knows the answer'.
We are here as friends but not necessarily the experts

jan
edit - Hi BlissBites - I just found another way to help Kiva - if your son's entrepreneurship class has cash to spend, they can also donate 'gifts in kind' - perhaps they would like to check out
Kiva's Wish List at Amazon.