I wasn't able to find anything in the official help file, or in the special help file I have that contains undocumented commands/identifiers, but this code worked for the testing I did.
It's a bit more complex than necessary, but it allows for multiple words.
Code:
alias alphabetical {
  if !$1 { .notice $nick You must specify one or more words }
  else {
    var %a = 1, %b = $0, %sorted
    while %a <= %b { 
    var %alpha1 = $($+($,%a),2), %c = 1, %d = $len(%alpha1), %alpha2
    while %c <= %d {
      %alpha2 = $+(%alpha2,$mid(%alpha1,%c,1),$chr(32))
      inc %c
    }
    %alpha1 = $sorttok(%alpha2,32)
    %sorted = $+(%sorted,$chr(32),$remove(%alpha1,32))
    inc %a
  }
  $iif($isid,return,echo -a) $1- sorted is %sorted
}