Encoding of hash in El-Gamal signatures

In section 5.2 of rfc2440, the process of calculating signatures is outlined. 
However, it
is not specified how to convert from the hash to algorithm-specific signature 
input for
all algorithms. It is for RSA (PKCS#1 padding +  DER -encoding of an ASN.1 
DigestInfo) 
and DSA (trivial). For El-Gamal, it doesn't say. I know that GnuPG uses 
an aproach similar
to RSA.

What is the story? How do I convert the hash to El-Gamal input?

Regards
/Bo