assignments

[dxs@evolving.com (Dan Stanger)]

i have data that is presented to me in a list which i had intended
to put into a structure.  the structure elements are
month day year hours minutes dur-hour dur-tenths tgn
i could also put this into a clos class.
i then want to store them into a record that will be passed to a c function
with the following elements.
month day year hours minutes duration tgn
where duration = dur-hour*600 + dur-tenths.
my lisp structure is l and my c structure is c.  is it possible to code this
so i dont have to refer to each element of the structure in the
assignment so i can assign month to month, day to day ... except for
the duration where i need to execute the above formula for duration?
or possibly to automaticly generate the assignment code with a macro
except doing something special for duration?
thanks,
dan stanger