compiling ports with --sysroot= and -isystem

[Julian Elischer]

How can I add entries (like the above) to a port compile?
I want to ADD things to CFLAGS.
If I add 'CFLAGS=...' to the build (for example, of lsof)  it actually 
replaces all the CFLAGS already there.
lsof (as the example) uses configure, so I would need to feed the 
added stuff into configure. Is there a standard way to do this?
In the environment I'm using, I'm building for a machine that is not 
the build machine, but an appliance.
It has a small number of differences in the include file contents, so 
I want it to compile using a different set of includes than those in 
/usr/include.

On the other hand I'm building a bunch of tools that do have t orun on 
the build machine and they need to use the regular /usr/include so I 
don't really want to replace them..


Julian

p.s. usual "please reply directly" comment applies.. I'm on this list 
but get it in digest form..