You could use Openjdk 1.6 from Fedora 16. Use this command:
yum install java-1.6.0-openjdk --releasever=16 --nogpgcheck (--nogpgcheck because yum complains of not having the key for Fedora 16, maybe there are better ways to solve this)
But this shows, that java-1.7.0-openjdk obsoletes java-1.6.0-openjdk and skips installation. And it shows that the package xorg-x11-fonts-Type1 is needed. So I did
yum install xorg-x11-fonts-Type1 and then I used the openjdk package which yum downloaded but refused to install because of the obsoletes warning
rpm --nodeps -ihv /var/cache/yum/x86_64/16/updates/packages/java-1.6.0-openjdk-1.6.0.0-68.1.11.5.fc16.x86_64.rpm (--nodeps for overriding the obsoletes warning)
Now I have both java 1.6 and java 1.7 on my system. Java 1.7 is my default. And Java 1.6 is in /usr/lib/jvm/jre-1.6.0-openjdk.x86_64/bin/java.
PS: There won't be any conflicts when you install both 1.7 and 1.6. The reason for removing 1.6 from Fedora 17 was, that OpenJDK6 will no longer get security updates after November 2012.