It isn't done. WinAVR ships with SRecord 1.38 because that is the
last version that did >not require the Boost libraries. Like you, I
did not see a Boost package for MinGW.
There is no package. Build from the boost instructions.
Goto the Boost Download site linked from http://www.boost.org .
Download boost_1_38_0, get the latest bjam executable in the
nxt86.zip package.
Get the PDF documentation for Boost if you want them. The link to
them is hiding in the lower left corner of the download page in the
'news' section.
Build with the TDM version of MingW (4.3.3 today). Put bjam in your
path, put mingw\bin in your path.
Unpack boost to boost_1_38_0. cd boost_1_38_0 mkdir build then run:
bjam --build-dir=build --toolset=gcc --build-type=complete stage
Come back in three to five hours later when it is done compiling
(which mine has now been doing for about ten minutes. I do this with
each release, it really does take *hours* to build boost. I needed
to update anyway).
I'll try building srecord after all the compiling is done.