The SCons wiki has moved to https://github.com/SCons/scons/wiki/CXXFile()

CXXFile() builds a lexer from a lex file, typically ending with .ll.

CXXFile( target='lex.yy.cpp', source='parser.ll' );

The result will be a C++ file named lex.yy.cpp which you can then compile and link with your project.