How do you open the trunk on a 94 jag xj6 when the key will not work and the battery will not take a charge?

I have a 95 Xj6 and I found this anwer:

"go to electrical accessorie supply sockets on left fender well beside small fuse box or on firewall beside hood latch on each side pull off rubber boot for access hook up posititivie jumper cable and find ground for negetive cable only leave hooked up for a few seconds to pop trunk push trunk button and remove cables (pg 98 of vehicle care book)".

Before finding this question, a mechanic told me that there was a place in the engine where you can hook up the positive cable to and then ground to the engine. Well, it looks like he is right. Best of luck.