Using GCC 4.9

I'm trying to install OpenMx, but it will not compile. For reasons that are complex and that I don't fully understand, I cannot use GCC beyond version 4.9, and having investigated on this forum, I suspect that this is the reason for the failure.

I tried to download an earlier version of OpenMx to see if that solved the problem, but the earliest version on CRAN is 2.2.2, from May 2015 (last year, for now!), and this still had the problem. Is there a a way to download an earlier version which might compile with 4.9? (Or is there some other way to persuade OpenMx to compile with GCC 4.9?)

Thanks,

Jeremy

More details: the errors relate mainly to the eigen package, and say things like:
(Note that I've simplified the paths a little).

C++ compilation of rule 'OpenMx' failed (Exit 1) [forge_remote_host=ioea14].
In file included from OpenMx/OpenMx/src/omxMatrix.cpp:30:
In file included from eigen3/Eigen/MatrixFunctions:59:
Eigen/src/MatrixFunctions/MatrixLogarithm.h:334:52: error: no member named 'Options' in 'Eigen::Map, 0, Eigen::Stride<0, 0> >'
static const int Options = DerivedNestedClean::Options;

Or

In file included from OpenMx/src/omxMatrix.cpp:30:
In file included fromeigen3/Eigen/MatrixFunctions:57:
eigen3/Eigen/src/MatrixFunctions/MatrixFunction.h:415:21: error: member reference base type 'ComplexMatrix' (aka 'int') is not a structure or union
result = Cresult.real();