This word is acceptable for play in the US & UK dictionaries that are being used in the following games:

• Lexulous
• Wordscraper
• Wordosaur

v. Present participle of highjack.

n. The seizure of control of a vehicle while it is in transit, either to rob it or divert it to an alternate destination.

n. robbery of a traveller or vehicle in transit or seizing control of a vehicle by the use of force

"After all, the so-called highjacking of the reward system is not itself a neurochemical process; it is a process whereby neurochemical events get entrained within in a larger pattern of action and decision making."

robbery   

buccaneering    piracy   

hijacking