Haven't tried this myself - but a 5 day pass will give 1.5 GB worth of 4G/LTE data plus free CSL WiFi access, unlimited local HK calls & credits for making overseas/IDD calls.
http://www.discoverhongkong.com/eng/...t-sim-card.jsp
Sim card is valid for 180 days & can be refilled (thus, pass on & shared with someone else within your friends & families, and/or business associates & co-workers/colleagues traveling ... ) It's available at HKIA on arrival & also numerous outlets & locations all over - at $88 HKD or about $12 USD - a pretty good deal & it has also promo offers.