Yes, with the 4-way tele mod you retain your current standard 3 tele positions (neck, neck in parallel with bridge, bridge), you just add one more combo: neck in series with bridge.
This little trick gives you some extra-boost and a very nice virtual humbucker sound in this position.
When you put two pickups in parallel, as in the most middle positions of pickup' selectors, the output drops a little bit under the output level of one of the two pickups involved.
To put both pickups in series, restores that level drop (even resulting louder than one of the single pickups involved), making it very useful for soloing or when an extra oomph or boost is requiered.
Being a virtual humbucker, same effects of humbuckers take place: some frequencies are boosted while others are cancelled so, the resulting sound will be fatter, warmer and less defined but always musical.
If both pickups have reverse magnetic polarity and reverse winding then, the benefite of hum cancelling is also there.
I just finished one wiring mod in my strato that works in two modes. First mode retains the stock 5 positions while the alternate mode gives me:
1. Neck in parallel with Bridge (Tele middle position)
2. Neck in series with middle (dark virtual humbucker)
3. The 3 pickups in parallel (very round and warm sound)
4. Middle in series with Bridge (Bright virtual humbucker)
5. Neck in series with Bridge (as per 4-way tele mod)
I'm gonna check how it sounds with a new loaded set of Mother's Milk, just this Friday and If I am satisfied with the mod (some doubts about out-of-phase positions), I am planning to hung a video to demonstrate the combos (but this last will take a while)