The jacking points are marked with an indented arrow on the underside of the sill, but for me, these weren't quite informative enough, so I've verified the info with wiser folk than me on the jaguarforums.com site.
Both pics are taken from the driver's side (of a RHD car), and applies to both V6 and V8 models (although the V8 might look slightly different, on the front area at least, as the earlier models seem to have more exposed bits rather than so much body-coloured material.
Front jacking points
Black box: this is the "lip" to aim for if using a portable jack.
Blue box: aim for this area if using a trolley jack (but be sure to use something on the jackhead to spread the load, block of rubber/wood/etc.
Green circle: this is what they use in the factory apparently, when the body is coming down the production line (some kind of prong-thingy inserts into that hole).
At the very top of the pic, in line with the black box, you'll see the indented arrow on the edge of the sill that the book refers to.
Rear jacking points
Yellow arrow: this is the "lip" to aim for if using a portable jack.
Red box: aim for this area if using a trolley jack (you want the area in between the 3 exposed bolts, on the black support plate. As with the front, use a flat piece of rubber/wood/etc to spread the load evenly across the jackhead.
At the very top of the pic, in line with the middle of the lip, you'll see the indented arrow on the edge of the sill that the book refers to.
Official pic from Jag