Can I fix the exponent in scientific/engineering format?

This is sort of a continuation of my search to find a ppm number format (http://www.excelforum.com/showthread.php?t=368806).

Found someone who mentioned using engineering formats (kind of an extension of scientific format). After a little tinkering, here's what I've found (using the values of 7E-3 and 7=-5 as examples):

format 7e-3 displayed 7e-5 displayed
.0E+0 .7E-2 .7E-4
0.0E+0 7.0E-3 7.0E-5 (REGULAR SCIENTIFIC NOTATION)
#0.0E+0 70.0E-4 70.0E-6 (EXPONENTS ARE MULTIPLES OF 2)
##0.0E+0 7.0E-3 70.0E-6 (EXPONENTS ARE MULTIPLES OF 3)
###0.0E+0 70.0E-4 7000.0E-8 (EXPONENTS ARE MULTIPLES OF 4)

and so on. Basically I can choose what the exponent is a multiple of.

Now what I would like to do is be able to pick the exponent explicitly. Using the example values above, I'd like to display (without changing the underlying value):

7.00E-3 0.07E-3

Does anyone know how to make this work, or am I just asking for too much??

No response. I guess I'm just asking for too much.