Making Thread Subject automatically contain the values of 3 custom thread fields

[ZiNgA BuRgA]

XThreads cannot do this by itself, but I'm interested in how you'd approach this.

Do you wish to hide the subject text box and force it's value to be made of the 3 thread fields?

Or do you want just the default value of the subject to be filled with the fields?  If so, how would it display when the fields haven't yet been filled out (as in the case when the user has just loaded the new thread page)?