Hi Peter

A coast 3 way is just one of 3 ways to hook up a 3 way ( someone once told me that why it called a 3 way " you can hook it up 3 different ways...I don't know if this is true ). Only two of the 3 are nec approve.

the coast 3 way uses the same type of swith- spdt its just wired different

Standard system
switch "a" hot to common, travelers to t1 and t2 switch "b" switch leg to common travelers to t1 and t2
coast system
Switch "A" hot to t1 switch leg to t2, common join to common of switch "B" hot from switch "a" join to switch "b" t1 much like a traveler would, the switch leg from switch "a" follow in the same manner to switch "b" t2.

maybe it may be better to say
Join common to common
Run your hot and switch leg the way you would you travelers.
what is neat about this system is you have you hot a switch leg on both ends, and in the middle as well. lets say you have a light above each 3 way and a 50' long hallway with a few lights alone the way. with only 4 wires running from box to box you have all you need.The neutral stays white, you make the black the hot red is the switch leg blue as the common. Using the coast as you can see save the "I start my 3way here with the hot and end it there with the switch leg and pull the switch back to the other light back at the start. then I'll run the hot over to the other end for my other light switches". With the coast system you have what you need at both ends.

hope that this will help its hard to explain this with text, If you and I was at a job site this would be a simple drawing on the wall.