Yeung Gor was very adept at learning martial arts very quickly. Just give him a few hints, and he can improvise pretty well. He was able to sort of reproduce a few strokes of Iron Palm Technique that way, and his learning of Dog Beating Stick Technique and East Heretic Wong Yerk See's key martial arts (Jade Flute Sword Technique and Divine Finger Snap) also occurred this way.
Over the years, Yeung Gor saw Gwok Jing using the Hong Lung 18 Palms on numerous occassions. He also witnessed North Beggar Hung 7 Gung using the palms at Mt. Hua. Based on these observations, could Yeung Gor kind of, sort of fake a few strokes of Hong Lung 18 Palms? He probably won't get the inner power generation and usage methods entirely right, but could he fake it enough to fool the inexperienced?