ok, were are you talking about.
the standard filter (non-ecc) has a big circle pan above the carb. with an inlet pipe coming up from the exhaust manifold. on this is your winter/summer switch.
to add a cone-filter adding the tube (will be hard as the rim of the hitachi carbs are ver minute and are very hard to be able to get a grip onto with your tube. (good luck with that) webber carbs are better for this as the rim is bigger. then dump your cone ontop of that.
the exhaust "hole" as so that in the winter the carb gets hot air blown into the carb so it doesnt "freeze", and blows direct external air from the atmosphere (directly infront of car) in the summer when ur driving along, "ramming" the air up and into the carb. there is no "special" way to do this. many have tried various ways. you can simply remove the plyable tube from the manifold heat shield and leave it open, or run a second tube up to the cone filter (but there is no point as you want it as cold as you can get it
)
no point running from grill as that way all your doing is ramming cold air at your axhaust manifold
personally, from lots of different tests, i found that the best position for the filter, is DIRECTLY ontop of the carb, the ma series engine seems to respond better this way.