Yes, of course.
My gcc/config/mips/t-mips file:
FPBIT = fp-bit.c
DPBIT = dp-bit.c
$(T)crti.o: $(srcdir)/config/mips/crti.asm $(GCC_PASSES)
$(GCC_FOR_TARGET) $(GCC_CFLAGS) $(MULTILIB_CFLAGS) $(INCLUDES) \
-c -o $(T)crti.o -x assembler-with-cpp $(srcdir)/config/mips/crti.asm
$(T)crtn.o: $(srcdir)/config/mips/crtn.asm $(GCC_PASSES)
$(GCC_FOR_TARGET) $(GCC_CFLAGS) $(MULTILIB_CFLAGS) $(INCLUDES) \
-c -o $(T)crtn.o -x assembler-with-cpp $(srcdir)/config/mips/crtn.asm
MULTILIB_OPTIONS = EB/EL
MULTILIB_DIRNAMES = eb el
MULTILIB_MATCHES = mel=EL meb=EB
EXTRA_MULTILIB_PARTS = crtbegin.o crtend.o crti.o crtn.o crtbeginS.o crtendS.o
LIBGCC = stmp-multilib
INSTALL_LIBGCC = install-multilib
dp-bit.c: $(srcdir)/config/fp-bit.c
echo '#ifdef __MIPSEL__' > dp-bit.c
echo '#define FLOAT_BIT_ORDER_MISMATCH' >> dp-bit.c
echo '#endif' >> dp-bit.c
cat $(srcdir)/config/fp-bit.c >> dp-bit.c
fp-bit.c: $(srcdir)/config/fp-bit.c
echo '#define FLOAT' > fp-bit.c
echo '#ifdef __MIPSEL__' >> fp-bit.c
echo '#define FLOAT_BIT_ORDER_MISMATCH' >> fp-bit.c
echo '#endif' >> fp-bit.c
cat $(srcdir)/config/fp-bit.c >> fp-bit.c
