http://www.ichotelsgroup.com/h/d/pc/...loscabos-_-iho

Looks like you just have to bring a printout of the special offer and present it at check-in.

Here is the full list of benefits

5,000 bonus points for each consecutive All-Inclusive Reward Night, up to 20,000 bonus points.
Two children under 12 are free when sharing a room with parents
Complimentary welcome amenity
An upgrade to Plaza Tower Ocean View room
25% discount on Spa Services at Natura Room at the hotel
$50.00USD credit towards outdoor activities with Bajaxplorer (per room per stay)
Early check-in and late check-out
Complimentary high-speed internet connection
Guaranteed specialty restaurant reservation