Here's a well-written and detailed discussion about Minecraft & Java including Java order, the Minecraft start stub, etc:
Make sure to use the latest Java:
Java for OS X Lion Update 1 (Java 1.6.0_29, updated 09. Nov.)
Java for Mac OS X 10.6 Update 6 (Java 1.6.0_29, updated 09. Nov.)
Java for Mac OS X 10.5 Update 10 (Java 1.6.0_26 on 64bit Intel, Java 1.5.0_30 last release for PPC)
Java for Mac OS X 10.4, Release 9 (only supports Java 1.5.0_19)
At this point it's a good idea to open Java Preferences and check which versions of Java are installed and what the preferred run order is. Sort it so that Java 6 64bit is on top, then Java 6 32bit, Java 5 64bit, Java 5 32bit.
Within Info.plist (see paragraph 2), find the 'JVMVersion' key and change it to '1.6+'. The next step is to replace 'JavaApplicationStub' in
with the one found in
Use 'Show package contents' and 'Go to folder' (⇧⌘G) to find those places.
Most people experience improved performance when switching to 64bit. Add a key to 'JVMArchs' with the value 'x86_64' on top of the existing ones to run Java in 64bit if it is available. This step is optional but recommended.