PZale summed it up perfectly. I don't really think they need specific work. If you do Olympic lifts correctly every pull finishes with a very explosive 'calf raise' under very high loads. Because of these points and the fact that the plantarflexion is occuring in a more natural movement pattern (following extension of the hip and knee) I think that OLs, sprinting, and jumping are easily enough to strengthen the gastoc-soleus complex.
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