The key is to replace /System/Library/Java/JavaVirtualMachines/1.6.0.jdk/Contents/Home/bin/java with a 32-bit mode only binary. My last resort is thinking how to disable the 64-bit capability of the binary so that only the 32-bit mode can be picked.
No matter how hard I tried, the Java 1.6 still runs in 64-bit mode.
