Ok just brushed up on the subject!
In most gnostic sects, Jehovah really is Yaldabaoth, the evil and ignorant demiurge who controls this world. He is ignorant of his own creation by Sophia, and therefore boasts all the time that 'besides me there is no other' etc. So, remember Jehovah is the bad guy here (I kinda like gnosticism because of that :). Naturally, the Serpent in the Genesis account
really is the hero of the story, because he brings knowledge (gnosis) to Eve, and then to Adam: knowledge that they are slaves to Yaldabaoth in his matrix paradise, and knowledge of the
Father of Lights in the realm above, the real god who gave them their divine spark and to whom they must return.
Of course, Yaldabaoth is pissed off by this subvertive action of the serpent and rapes Eve (he would try again later with Norea, Noah's wife). From this, Eloim and Yave are born, known to us as Cain and Abel.
Adam and Eve later have a son called Seth. He receives the gnostic secrets from Adam and becomes the father of all gnostics (i.e all the people who are aware of Yaldabaoth's matrix world and who cultivate their divine spark).
This is a somewhat upside-down version of the Serpent Seed: Yaldabaoth tries to destroy the Sethians throughout history.
NB: Keep in mind that there is no such thing as one gnosticism. There were a great many groups with conflicting views (most saw Jehovah as bad, though). The Ophites (or Naasenes)worshipped the snake as hero, the Sethians called themselves after Seth per above. On the other hand the Cainites didn't see Cain evil offspring but as a hero, like the serpent. Don't try to find any consistency here!
Hope this helps with your journey!
See the links for references to the gnostic texts where you can find these things.
Deus Mauzzim
Links:
http://www.timelessmyths.com/mirrors/gnostic.php
http://www.gnosis.org