@Riley_S 

Hi Riley, I'm really glad you replied. I didn't consider that I could just use these extra mains that I'm going to have on other single pole switches that are not three-way. Great idea!!

Yes, I spliced in the satellite where the 4-way switch would be.  Just connected both travelers to their respective screws on the extra satellite in the middle (traveler 1's together on Traveler 1 screw and traveler 2's together on the Traveler 2/load screw) and the whole system works perfectly.  Note, this is using the older 1.0 style.   I don't know how or if the newer version would work the same way.   

Would be great to see TP Link test this and add instructions if it is a legitimate use.   Also selling individual extra satellites for 4 and 5 way applications.

  @4wayman 

Hey thanks for all the info on this I have 3 - 4 way switches I have to wire with the ks230... so here I go ...

  @TH13 Just got an email from your reply.
 

I spent so much time on this that I went through the trouble of registering an account on here just to spread this gospel.  My greatest hope was that it would help at least one other person out there!   Good luck!  
 

Make sure you have the older version, the newer versions might not work with this strategy.  

  @TH13 were you able to get it working? If so, were you using v2 or v1 satellites? I'm using v2's because it's all I've been able to find. So far, I've only been able to get one satellite or the other to work (never both together). I'm going absolutely bonkers! I'm sure I'm just missing something stupid. This is what I'm looking at where the 4-way switch would be. There's a red and black wire coming from each 3-way.

  @DarkAngela 

Sorry, this does NOT work with the V2.  And the V1 appears to no longer be available anywhere.  Don't bother trying to buy V1 on eBay or Amazon, they are all DOA units that were returned and are being resold.  
 

I had one of my V1's stop working and tried to replace it a few weeks ago but was not able to find one.

I ended up just abandoning the 4-way by tying the reds and whites together in the 4-way box and essentially turning it back into a 3-way setup.  Not ideal. 
 

TP LINK, FFS, sell a multi-location dimmer. 

  @TH13 

In a 3 way/4way setting, all you have to do is change out the 3 way switch at the end of the run and it will work for the whole string. Don't touch the 4way switch at all. The 4 way switch has 4 wires to it, basically just two pairs of travelers in and out. Leave those alone.

  @DarkAngela 

Don't touch the 4 ways, just replace the 3 way switch with the KS230.....done.

  @Clffhnger Not really.  You can bypass the four-way switch completely by combining the traveler wires permanently inside the junction box. But if you leave the four-way in place, the satellite at the load side will only work when the four way switch is in the right position.  When it it switches it will cross the wires and the satellite won't function.