Add to peds.ide:
907, OFYSKP, OFYSKP, CIVFEMALE, STAT_SUIT_GIRL, busywoman, 120C,0, man,4,0,PED_TYPE_GEN,VOICE_GEN_SOFYBU,VOICE_GEN_SOFYBU
908, OMYSKP, OMYSKP, CIVMALE, STAT_SUIT_GUY, man, 120C,1, man,4,4,PED_TYPE_GEN,VOICE_GEN_SOMYBU,VOICE_GEN_SOMYBU

Peplace the prompt in pedgrp.dat:
OFYSKP, OMYSKP								                        # Shopkeepers