How to use "setuid-program"?

[Matthew Brooks]

The old way of doing setuid programs:

(setuid-programs
  (cons
   #~(string-append #$slock "/bin/slock")
   %setuid-programs
   )
  )

now gives a deprecation warning as follows:
>warning: representing setuid programs with file-like objects is deprecated; 
>use 'setuid-program' instead

The actual manual, however, still lists the old way as the way to do it. As 
such, I haven't been able to work out what sytax is actually expected for 
defining a setuid program with "setuid-program".

I assume that someone familiar with guile could probably check the definition 
of "setuid-program" or something to determine what it expects, but I have no 
idea how to do that either.