grubinst.exe is a console mode program to install GRUB4DOS boot code to the MBR or partition boot sector.
I downloaded it from GRUB4DOS project page grubinst_1.0.1_bin_win.zip, and I think its for 32 bit windows.
But I can run it in 64 bit ubuntu
$ ./grubinst.exe --version
grubinst version : 1.0.1