Here is the new patch (doc strings added) :
pyOpenSSL-0.7-pkcs12.patch
pyOpenSSL-0.8-pkcs12.patch (updated 29/03/2009)

The synopsis is still the same :

p12 = crypto.PKCS12()
p12.set_privatekey(pkey)
p12.set_certificate(cert)
open("test.p12", "w").write(crypto.dump_pkcs12(p12, "my_passphrase"))