I tried to build the Boost library for native 64bit using MinGW64 compiler, but got some failures. Any pointers are appreciated. Thanks.
I got the bjam.exe (b2.exe)
This is a known issue for building Boost >~1.51 with MinGW. At the moment, building Boost with MinGW is broken because Boost has a dependency on MASM (in your case ml64) when building Boost::Context for Windows, even with MinGW.
As a bodge you can get MASM from the Microsoft Website: http://www.microsoft.com/en-gb/download/details.aspx?id=12654 for a 32-bit version, or else the Windows Driver Kit for the 64-bit version: http://msdn.microsoft.com/en-us/windows/hardware/hh852365.aspx
You can use the patch provided on the Boost bug tracker here: https://svn.boost.org/trac/boost/ticket/7262 though to make Boost::Context compile with just MinGW, thus re-enabling cross-compilation of Boost. You can also read the responses by Boost's Olli on the subject and his response to the subject. Don't expect anything to be fixed in Boost for a while at least!