The Carbide.c++ > Build page in the Preferences window provides an option to use the local x86 build tools for each emulator build. A directory named x86Build at the root of the product installation contains the build tools, libraries, and env_update.exe file.
Uncheck the "Use built-in Nokia x86 environment variables for WINSCW builds" option if you do not want to use the built-in compiler.
Figure 1 shows the Build preferences window.
Figure 1 -Build preferences window showing Emulator Build Options