Is it possible to select the last n items with nth-child?

Using a standard list, I'm trying to select the last 2 list items. I've various permutations of An+B but nothing seems to select the last 2:

li:nth-child(n+2) {} /* selects from the second onwards */
li:nth-child(n-2) {} /* selects everything */
li:nth-child(-n+2) {} /* selects first two only */
li:nth-child(-n-2) {} /* selects nothing */

I'm aware of a new CSS3 selectors like :nth-last-child() but I'd prefer something that works in a few more browsers if possible (don't care about IE particularly).

This will select the last two iems of a list:

li:nth-last-child(-n+2) {color:red;}

<ul>
  <li>fred</li>
  <li>fred</li>
  <li>fred</li>
  <li>fred</li>
  <li>fred</li>
  <li>fred</li>
  <li>fred</li>
  <li>fred</li>
</ul>

nth-last-child sounds like it was specifically designed to solve this problem, so I doubt whether there is a more compatible alternative. Support looks pretty decent, though.

:nth-last-child(-n+2) should do the trick