Hello
You can do it but you have to manually adjust the settings.
Basically for HC12 you have to remove the option -D__NO_FLOAT__ from compiler command line and add floating point format option (if needed) then replace ansi library file.
To retrieve the appropriate ansi library file check the file readme.txt from {Install}\lib\hc12c.
Re-creating the project with the wizard is just easier and avoid any discrepancy between compiler options and library file.
CrasyCat