I once wanted to do something like this and contacted DL via phone. At their suggestion, I applied for DL to make the charitable donation. There is a place on the site for the request. It took about six weeks, but DL came through and donated the certificates to be auctioned, at no cost to my account.

FWIW, it was coupled with a Marriott certificate for which I did have to fork over points. It raised several hundred dollars for (local charity in Atlanta).

You might want to try that route.