How to temporarily disable IPV6?

[Bryan Pizzuti]

I need to test something. PREFERABLY I'd just like to disable it quick, do
the test and then bring it back, or reboot and have it come back (Unless I
need to remove it permanently anyway, but then it's just going to come out
of my eventual custom kernel). I was thinking about my problem accessing my
news server and realized that all the Linux builds I'm trying with it have
IPv6 going, while WIndows doesn't, and I'm wondering if that's what's making
my news server ditch my connection request. (Silly of my ISP, I know, but I
should at least test it). 

Incidentally, simply modprobe -r ipv6 doesn't work since it's in use. ;)
Bringing the eth0 and lo ports down before modprobing it doesn't work
either.