Perhaps if I do a tiny bit of docco, others may follow?

doc/ssl.pod

@@ -310,7 +310,22 @@ protocol context defined in the B<SSL_CTX> structure.
 
 =item long B<SSL_CTX_set_tmp_rsa>(SSL_CTX *ctx, RSA *rsa);
 
-=item long B<SSL_CTX_set_tmp_rsa_callback>(SSL_CTX *ctx, RSA *(*cb)(void));
+=item SSL_CTX_set_tmp_rsa_callback
+
+C<long B<SSL_CTX_set_tmp_rsa_callback>(SSL_CTX *B<ctx>, RSA *(*B<cb>)(SSL *B<ssl>, int B<export>, int B<keylength>));>
+
+Sets the callback which will be called when a temporary private key is
+required. The B<C<export>> flag will be set if the reason for needing
+a temp key is that an export ciphersuite is in use, in which case,
+B<C<keylength>> will contain the required keylength in bits. Generate a key of
+appropriate size (using ???) and return it.
+
+=item SSL_set_tmp_rsa_callback
+
+long B<SSL_set_tmp_rsa_callback>(SSL *ssl, RSA *(*cb)(SSL *ssl, int export, int keylength));
+
+The same as L<"SSL_CTX_set_tmp_rsa_callback">, except it operates on an SSL
+session instead of a context.
 
 =item void B<SSL_CTX_set_verify>(SSL_CTX *ctx, int mode, int (*cb);(void))