Can not use New luancher on my mac

Hello. I have recently got the new Minecraft Luancher for my MAC OS X, MinecraftDev.dmg. When ever i try to open the lunacher it gives me this msg.:
This application requires java 1.6 or later , but only the following java versions are installed: 1.5.0, 1.4.2, 1.5, 1.4. Updating to a newer version of Mac OS X May resolve this. ::::
Anyways, i got that msg. But the thing is I can not update my mac and yes i have tried but it keeps saying ::

software Update doesn't have any new software for your computer at this time.

It says that everytime If you could please maby help me run The luancher on java 1.5 like it used to or do anything else that would resolve this that will let me play the new luancher, That would be helpful to. Thank you - Devin