Patristic Greek

I am posting this question on behalf of a colleague who is reading more 
these days in patristics (esp. Origen) than in the NT. He wants to know 
if there are any helpful resources that anyone knows of for reading 
patristic Greek (what lexicons are most useful, grammars, etc.).

Philip Graber
Graduate Student in New Testament	Graduate Division of Religion
Emory University			211 Bishops Hall, Emory University
pgraber@unix.cc.emory.edu		Atlanta, Georgia 30329 USA