Apparently there was a branch of Theravada in Cambodia that employed some tantric-like practices, including visualizing oneself as the Buddha and taking on the Buddha's qualities (what Tibetans call deity yoga).
Crosby, Kate. (2000). Tantric Theravada: A bibliographic essay on the writings of François Bizot and others on the yogvacara Tradition. Contemporary Buddhism
See here: http://tinyurl.com/2e7lvgc