Modify the line 315 of rom_sbs.pl to access cpp.exe when not building for Unicode.
EXPORTS
?Export1@@YAHXZ @ 1 NONAME ; int __cdecl Export1(void)
?Export2@@YAHXZ @ 2 NONAME ; int __cdecl Export2(void)
?Export3@@YAHXZ @ 3 NONAME ; int __cdecl Export3(void)
?Export4@@YAHXZ @ 4 NONAME ; int __cdecl Export4(void)