jpackage can't handle 64 bit java is what I have found. Even so, it's perfectly possible to get it installed. All you need to do is download the jdk straight from sun and install that. Installation instructions can be found at their site. You'll have to update /etc/alternatives manually after that.
If you prefer having jdk integrated into your system, you should go with either Debian of openSuse (mine are using jdk6 at this time, I simply had to install from their repos).
You may also want to consider whether it's interesting at all to run 64 bit java as it has some missing features. If you go 32 bit java, then I recommend using 32 bit Debian (yes 32 bit - it is faster than any of the 64 bit systems I'm running; also 64 bit Debian takes extra work to run 32 bit apps) or openSuse 64 bit, which easily integrates 32 bit applications.