Here is the short version:
1. su – oracle
2. Go to the location where you donwnloaded wls1211_generic.jar (I’ve downloaded it to /home)
java -jar -Xmx1024m -XX:MaxPermSize=512M wls1211_generic.jar
Important: if you do not set PermSize as well as Xmx, your install will fail with Out of Memory errors.