Before posting this, I saw that you have replaced the entire contents of your post with an entirely new question. Please see How do I change/delete my post?, in particular "It is uncool to update a node in a way that renders replies confusing or meaningless". Because I already put some effort into my answer I am posting it anyways, and have considered your node for editing. (Update: It appears you edited your post multiple times and the version I saw was not the original. The same comments apply to those edits too.) Please post your new question in a new thread.

Trying to figure out a way to do an my $ldif = Net::LDAP::LDIF->new ... on the output of an exec qx ...

system qx[...];
[download]

Should I be using an System or Exec? I think I should be doing something like this, but use the ldap::ldif->new with EXEC?

Both system and qx// call external commands, so what this code is trying to do is run a command with qx[], get its entire output, and feed that as the arguments to a system command, which is almost certainly not what you want. I of course don't know this custom external dxsearch tool you are using and I am not an expert on Net::LDAP::LDIF, but its documentation does make clear that you can give Net::LDAP::LDIF->new a filehandle instead of a filename. Based on your description, in this case, that filehandle could come from, for example, a piped open, which I describe in my post here along with lots more on running external commands, which I also strongly recommend you check out.

I want to use perl to process the large ldif it creates and format it into a csv report.

Since the code you showed doesn't use it, I recommend Text::CSV (also install Text::CSV_XS for speed).