1. Get dexdump.exe from http://dex-decomplier.googlecode.com/files/dexdump.zip
2. Get UNDX tool undx.jar from http://www.illegalaccess.org/undx/
3. Convert dex bytecode to java bytecode using
java -DASDKLoc={Location of dexdump} -jar undx.jar {dexfile}
this tool generate dex dump file {dexfile.dump} and java bytecode archive {dexfile.jar}.
4. Get Java Decompiler JD-GUI from http://java.decompiler.free.fr/?q=jdgui and use it to decompile {dexfile.jar}