Found in Gadadhar Pran's commentary to GLA, Introduction to Madhyahna lila.
sevAsya yogya-vapuSAnizam atra cAsyA
rAgAdhva-sAdhaka-janair manasA vidheyA
I have followed the direction of Sri Rupa Goswami’s Smaraëa-mangala to elaborate on Radha Krishna’s ashtakala lilas. Raganuga sadhakas should perform manasi seva of these pastimes while mentally conceiving their siddha deha fit for serving in the lila. (Gla. 23-94)
Srila Vishwanath Chakravarti’s granddisciple, Sri Vrindavan Chakravarti, in his commentary on this verse, glosses the words yogya-vapuSA as, “in the suitable siddha-deha fit for serving within the lila, received through the guru’s instruction” (zrI-gurv-AjJA tat-sevA-yogya-siddha-vapuSA).