Although everyone thinks of dipodic verse to be the long Victorian lines favored by Tennyson and Gilbert, it can be used to describe any line that can go both ways. So
I
am the
very
model
of a
modern
major
gener
al
is the technical meter but
I
am the very
model of a
modern major
general
is how it's actually said. Stallings talks about it
here. Perhaps this is what Jonathan means between the poetic meter and "how one would naturally read the line without it".
Some linguists divide stresses into 4 categories (first stress, secondary stress, and so on) but only so they can write long papers on stress patterns and rules in English. In poetry, the ear is all that matters. Thinking about it too much isn't going to get one anywhere.