Aww I thought you had my answer, but sadly that is not what I am talking about. What I mean is I want to aim with the mouse like a normal FPS game with a target/reticle in the center of the screen
As far as I know, Daggerfall doesn't support reticles. But from my experience, it's not particularly necessary. Most interactive objects are large enough that simply centering them on the screen is enough. For the comparatively rare cases when that's not adequate, just use the cursor mode.
If you absolutely, positively have to have a reticle, you could always take the low-tech approach and affix a small piece of clear tape with a dot to your monitor. That's the best you're going to get until either DaggerXL is released or somebody decides to code game-independent reticles into DOSBox.