Some notes on the building xerces 2.8.0 on Solaris. You can find the build instructions on the xerces site. But there's some changes that are needed to make it work with recent Studio compilers.
Makefile.incl. This is a deprecated option and should be removed from the Makefile.
Makefile.incl. Need this flag on the compile and link lines in order that stlport4 is used instead of the default libCstd. Most recent C++ codes require a more up to date version of the Standard Library than the default provides.
runConfigure. This stops the compiler from emitting a warning message about deprecated options.
$ ./runConfigure -p solaris -c cc -x CC -r pthread -b 64
Hopefully this gives you sufficient information to build the 2.8.0 version of the library.
Update: On 19th March 2015 they removed the 2.8 branch of xerces. So the instructions are rather redundant now :)