In scons yes, since it is rather more sophisticated than other systems in that regards.Actually, those are for non-directory flags, e.g. debugging, optimization etc. scons uses CPPPATH and LIBPATH for the search paths.
Well, you can't do that, because you can't pass arguments multiple
times
to scons, but as of r554 it will accept 'include' and 'lib' options to
add to the include and library paths respectively. If you want to add
multiple directories, you can join them with the ':' character (';' on
Windows) as per usual.
BTW, apparently Options is deprecated and one is supposed to use
Variables instead. There is a ListVariable which might be able to do
the right thing (allow a list of validated directories), but I can't
really tell from the documentation as it is exceedingly minimal.
Anyway, this is a good step. Thanks.