Hi Dave,
As Denis indicated, I don't think that'll be needed,
at least as far as Guide is concerned. You could, for
example, apply Denis' program to cut down the size of
'mpcorb', then run Guide and ask for a table of asteroids
down to a given magnitude (Tables... Current Asteroids),
and click on the "RA" table header to sort the list by
RA. You can then quickly see what's between a given
pair of RAs.
Now, as to omitting objects too far to one's south
to be visible... there's another poorly-documented
feature here: the ability to filter asteroids by
RA/dec rectangle. It's described at
http://www.projectpluto.com/update7.htm#asteroid_filtering
After the initial discussion of filtering asteroids by
orbital elements, it mentions that one can set up a filter
to include only asteroids within a given RA/dec box, or
within an RA range and above a given declination.
This ability to filter asteroids can be quite powerful
and, with modest effort, can let you do all sorts of
clever things such as "show only Trojan asteroids close
to opposition" and such. It may take you a few tries to
get used to it, though.
-- Bill