[Bastiaan]

If your mixer has line-in's and direct outs, wich are post-eq it is easy. Just choose a plugin, but instead of plugin, choose i/o and choose a port (lets say 3). this will rout the audio out of output 3 and back into input 3. After that it will flow through your protools fader....so its a bit like an insert on an analog mixer...

To find out if your direct out's are pre or postfader is simple. Do the routing "trick" and dial in some extreme eq....you should be able to hear it... Some mixers are switchable for pre or post eq on their direct outs...

Hope this helps