In the UI there is no ability to multi-select and change the Content column. (Admittedly not an optimal situation.)
You can, however, FILTER the Publishing Wizard dialog to show only the packages you have selected (which may help) -- at least makes the list contiguous.
Now, another part of this is the =700= packages to be published. In all probability only a handful of those 700 packages will actually be applicable to your systems. Driver packages are matched by HardwareID (and Dell packages, specifically, are matched through WMI queries), so if you can determine the installed Hardware IDs in your systems, you can use that to pre-select the packages that need to be published and likely eliminate a significant number of those packages that will never be relevant.
We are definitely interested in your feedback and suggestions on how the dialog can be improved to meet this particular use-case.