No you can't use them together. If you use Detect, Protect or Endure, using *any* of them again will make the accuracy 50%.

So it could work for a few turns but will fail pretty quickly. The chance of succeeding 3 times in a row is only 25%.

You should alternate Protect with an attacking move. You're still only taking a hit every other turn, so Toxic should work its magic.

Note: prior to Generation IV, the chance of each one drops by 50% each time, i.e. first it's 100% then 50% then 25%. So the chance of hitting 3 times in a row is even less at 12.5%.