to install git on CentOS, simply follow these instructions:
yum install gettext-devel openssl-devel expat-devel curl-devel zlib-devel
wget http://git-core.googlecode.com/files/git-1.8.0.tar.gz
tar xzvf git-1.8.0.tar.gz
cd git-1.8.0
make prefix=/usr/local all
make prefix=/usr/local install
[root@server1 git-1.8.0]# whereis git
git: /usr/local/bin/git