|The following is based on information from Fallout Tactics.|
In reality the perk increases the Perception of a deathclaw by 2 permanently. You just have to be a deathclaw to take this perk.
You can not select/aquire this perk playing as a deathclaw because it requires 5 IN. If you want to earn this perk in game you must change the file "races.txt" in the folder "Fallout Tactics\core\tables" and search for "statbase_Deathclaw", then under the "I" (which is INT) you'll see: the first number is the minimum allowed for that stat; above is the default starting stat for that race; finally, is the maximum allowed by the game for that stat. This last should be 4, you can change it to 5 and this allow your deathclaw having up to 5 IN. If so, now it is able to select this perk.