By script: sure! This was a bit of fun.
Place your text cursor into your numbered list as it is now, and be sure to place it inside the first numbered paragraph that should be changed. This script scans to the end of the current list, then reverses the list, putting the first number (which may not be '1'!) into the last item and counting down as it goes up to where you started the script.
(Copy, paste into a plain text editor — Notepad, Textedit in plain text mode; best is Adobe's own ESTK Editor –, save as “ReverseNumberedList.jsx” into your User Scripts folder; it should automatically appear in the Scripts panel.)
if (app.selection.length == 0 || !(app.selection[0] instanceof InsertionPoint))
{
alert (“Please place the text cursor in the first paragraph with a numbered list…”);
exit(0);
}
firstp = app.selection[0].paragraphs[0];
if (firstp == null || firstp.bulletsAndNumberingListType != ListType.NUMBERED_LIST)
{
alert (“That's not a numbered list…”);
exit(0);
}
lastp = firstp;
while (lastp.paragraphs.nextItem(lastp) != null && lastp.paragraphs.nextItem(lastp).bulletsAndNumberingListType == ListType.NUMBERED_LIST)
lastp = lastp.paragraphs.nextItem(lastp);
// Reached the end of this numbered list. So…
var count = firstp.numberingResultNumber;
do
{
lastp.properties = ({numberingContinue:false, numberingStartAt:count});
count++;
if (lastp == firstp)
break;
lastp = lastp.paragraphs.previousItem(lastp);
} while (1);