Just in case anyone is interested, here is the complete set of calculations you can use to convert from milliequivalents per kilogram per day to teaspoons of salt per fluid ounce of formula.  As it turns out, the final answer is something like 0.5 - 1.0 teaspoons of salt per 24 fluid ounces.  We’re using 1.0 teaspoon of salt per 24 fluid ounces of formula so that’s about right.  As long as formula consumed per day is roughly proportional to the baby’s weight the final answer should be about the same.

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http://www.themeter.net/conv19_e.htm

1 gallon      = 3.785  liters      = 4 quarts

1 quart       = 0.9464 liters      = 2 pints

1 pint        = 0.4732 liters      = 2 cups

1 cup         = 0.2366 liters      = 8 fluid ounces

1 fluid ounce = 29.58  milliliters = 2 tablespoons

1 tablespoon  = 14.79  milliliters = 3 teaspoons

1 teaspoon    = 4.929  milliliters

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http://www.saltinstitute.org/15.html

composition of salt      = sodium chloride

molecular weight of salt = 58.44   grams/mole

density of salt          = 2.165   grams/cubic centimeter
                         = 2.165   grams/milliliter
                         = 0.03705 moles/milliliter
                         = 0.1826  moles/teaspoon
                         = 182.6   millimoles/teaspoon

density of salt          = 182.6   milliequivalents/
                                   teaspoon
                                   (NaCl is one-to-one)

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http://www.vet.ohio-state.edu/docs/fluids/part7/part7.html

From Moles to Milliequivalents

Many important substances in the body are measured in
equivalents. The technical definition of an equivalent is
the amount of substance it takes to combine with 1 mole of
hydrogen ions. As an example, we can look at hydrochloric
acid (HCl). It takes approximately 35 grams of chloride
(1 mole), to combine with 1 gram of hydrogen (1 mole) to
make 1 mole of HCl (which weighs approximately 36 grams).
Since both of these elements are monovalent (carrying a
valence charge with a magnitude of 1), they combine in a
one-to-one ratio. Therefore the amount of chloride that is
needed to combine with one mole of hydrogen is 1 mole or
1 equilvalent (eq).

As another example, let’s say you have a divalent ion
(Ca+2) combining with Cl- (a monovalent ion) to form
calcium chloride (CaCl2). The combining ratio of calcium
to chlorine is one-to-two, meaning it takes half a mole of
Ca+2 to combine with one mole (or 1 eq) of Cl-. So, half a
mole of calcium equals 1 equivalent.

Another way to look at it is to say one equivalent is the
amount of ion required to cancel out the electrical charge
of an oppositely charged monovalent ion. You can also say
that the valence charge of the ion is the number of
equivalents there are in one mole of that ion. For
example, nitrogen (N-3) is a trivalent ion; therefore one
mole of nitrogen equals 3 equivalents. Using the calcium
example from above, we know that one mole of calcium
equals 2 equivalents.

Equivalents can also be defined in terms of metric weight.
The weight of one equivalent can be determined by dividing
the gram-atomic weight of the ion by its valence. For
calcium, the equation would look like this:

We know that calcium weighs approximately 40 g. Since 1
equivalent of calcium is half a mole, we can see that
1 equivalent weighs approximately 20 g.

Remember

Most solutes in the body are not measured in grams and
moles, but milligrams and millimoles instead. So we can
use the term milliequivalent when discussing such
substances. Here are some things to keep in mind when
converting to milliequivalents:

1 meq = 10-3 eq
For monovalent ions, 1 meq = 1     mmol
For divalent ions,   1 meq = 0.5   mmol
For trivalent ions,  1 meq = 0.333 mmol

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http://www.emedicine.com/ped/topic1931.htm

salt supplementation = 20-40 milliequivalents/kilogram/day

Baby’s weight        = 15 pounds = 6.8 kilograms
(EXAMPLE)

salt supplementation = 136-272 milliequivalents/day
for baby

density of salt      = 182.6 milliequivalents/teaspoon

salt supplementation = 0.75-1.5 teaspoons/day
for baby

food intake of baby  = 38 fluid ounces/day
(EXAMPLE)

amount of salt to    = 0.5-1.0 teaspoons/24 fluid ounces
add to formula