So after you added the chmod and rebooted, your /system and /system/bin file became 0777? If so then you can adb push su to the /system/bin folder. After that in the same file you chmod you can add:
chown root.root /system/bin/su
chmod 06755 /system/bin/su
reboot again and verify by adb from a command prompt that su is owned by root and is rwsr-sr-x by doing the following (press return after each line):
when you return on the ls -l the screen will scroll fast. use your page up button to search for su and see its permissions.
If all goes well, then you can install superuser.apk and install busybox...oh, and that means your rooted.