This is an old revision of the document!
MPIR is built using VC9 projects files. No patch are necessary but to rename the library to mpir_a.lib. Follow the instructions in the readme.txt in the MPIR sources and build “lib_mpir_p4” to get the static library we use for PHP.
The modified sources (only renamed the mpir.lib in lib_mpir_gc to mpir_a.lib) is available here.