You should stop worrying about the procedure being
too tough and being more of a psychoanalysis test.
The IIM Personal Interview only aims to determine
the following key factors:

1) Are your goals in line with what the institute can
offer: What are your goals? This is the most
important question you can ask yourself. Your
decision to do an MBA should be a natural
progression in your scheme of things. So if you want
to be finance professional, list down the different
niches of finance that you feel interested in.
Remember you don't have to be 100 % specific about
your goals. The IIM panel is wise enough to know
that you are not truly sure of exactly what you want
to do right out of college (just as they once did) and
so make at least a list of 3 things that you feel you
find interesting and want to work towards learning
in your MBA

2) How do your academics/technical skills
complement your goals: If you are an engineer you
can stress upon your quantitative approach towards
your work and how you find finance an interesting
choice given your love for maths. If you are from an
commerce background you can stress upon your
knowledge of accountancy and its relevance in the
field of investment analysis, private equity and
merchant banking and how you intend to add to
your knowledge regarding the specifics of these fields
through your MBA