Compile bitcoind https://github.com/bitcoin/bitcoin/archive/v0.8.6.zipLeveldb libraries will not compile automatically so we'll need to compile them first.
Extract bitcoin-0.8.6.zip (for example to C:\) then start MinGW shell and change into leveldb folder:
cd /C/bitcoin-0.8.6/src/leveldb
TARGET_OS=NATIVE_WINDOWS make libleveldb.a libmemenv.a
this will compile both libleveldb.a and libmemenv.a libraries required by bitcoin.
About this part... actually there is already a directive in the makefile.mingw that does exactly that... from msys while in the bitcoin src directory, call:
make -f makefile.mingw leveldb/libleveldb.a