SOLVED my own problem by modifying the hphp2k12.inf file to include these lines:
[Models]
"hp photosmart 140 series"=hp_Install_140,HPPHOTOSMART_140_SER0FDA
"hp photosmart 240 series"=hp_Install_240,HPPHOTOSMART_240_SER002A
;back port
"hp photosmart 7200 series"=hp_Install_7200,HPPHOTOSMART_7200_SE5294
"hp photosmart 7600 series"=hp_Install_7600,HPPHOTOSMART_7600_SE842D
"hp photosmart 7700 series"=hp_Install_7700,HPPHOTOSMART_7700_SE80FD
; ADDED FOR 7760 test
"hp photosmart 7760 series"=hp_Install_7700,HPPHOTOSMART_7700_SE80FD
; ADDED FOR 7760 test
"hp photosmart 7900 series"=hp_Install_7900,HPPHOTOSMART_7900_SE779C
;front port
"hp photosmart 7200 series"=hp_Install_7200,HPPHOTOSMART_7200_SE8FD3
"hp photosmart 7600 series"=hp_Install_7600,HPPHOTOSMART_7600_SE3DC4
"hp photosmart 7700 series"=hp_Install_7700,HPPHOTOSMART_7700_SEA1C1
"hp photosmart 7900 series"=hp_Install_7900,HPPHOTOSMART_7900_SE49F7