Quote: "I want to move a character to one of 4 random positions when stepping in a trigger zone. "
Quote: "The only "teleport" commands available in vanilla FPSC are for the player. "
So, if you cannot move the character, then emulate him. (make copies)
If you had the four instances of the character set up to spawn at their locations then a simple spawn destroy would do.
Then you would simply spawn the proper one based on a random=x condition.
Four of those in the same state with each one representing the activation of the proper character location to spawn.
So whichever random=x hits first would spawn the new character at the right location and then move out of that state and to one that then destroys the host.
The health adjustment could be handled as well by using a global variable and then adjusting the new characters health based on that variable.
I think it could be done in Vanilla FPSC with a little effort.