I'm using a small tool when running in issues like this. It has been very helpful and could easily adapted to most environments:

#!/usr/bin/perl
print "Content-type: text/html\n\n";
for (sort(keys(%ENV))) {
 print "$_ = $ENV{$_}<br>\n";
}
[download]

Apache used to write the method used to a enviroment variable. I never tried Apache on Windows for this, but you could test it easily.

Once you got the method, all you need is a simple if...