Setting environment and support of older OS/arch

[Eckard Brauer]

(1) How is it possible to not only set a compiler using "port select",
but add some -I directives too?

Problem is that, using Tiger 10.5.8, nearly every relevant thing is
below /opt/local (e.g. STL), but gcc consequently takes include files
from /usr/include, so compilation will fail often.

A maybe clearer variant of this question would be: Is it possible to
replace (better: overlay in the sense of an overlay fs) system tools
with those from macpports, as the current strategy seems to enforce
consequent confusion?

(2) As ports is of course more focused on recent OS', is/are there (a)
branch(es) or related project(s) focusing on support of older ones?
Maybe that could make things easier, even with the risk of drifting
apart, but either I'm still ignorantly missing that, or there's none...

Thanks in advance,
Eckard