brew install V8 fails on 10.5.8

[barracuda156]

After I have installed tigerbrew on 10.5.8, I tried install V8 (which I desperately need on 10.6 PPC, so I thought to install it on 10.5.8 first), and that failed:

36-137:~ arjuna$ ruby /Users/arjuna/Desktop/install
==> This script will install:
/usr/local/bin/brew
/usr/local/Library/...
/usr/local/share/man/man1/brew.1

Press ENTER to continue or any other key to abort
==> Downloading and Installing Homebrew...
% Total % Received % Xferd Average Speed Time Time Time Current
Dload Upload Total Spent Left Speed
100 1922k 100 1922k 0 0 157k 0 0:00:12 0:00:12 --:--:-- 213k
==> Installation successful!

36-137:~ arjuna$ brew install v8
v8: OS X Lion or newer is required.
Error: An unsatisfied requirement failed this build.