With a little modification, your alias will work the way you want it under v7.1:
Code:
alias chr { 
  var %r = $!+( $+ $left($regsubex($1-,/(.)/g,$+($,chr,( $+ $asc(\1) $+ ),$chr(44))),-1) $+ )
  noop $regex(%r,/\54(.*))/) | var %x = $+($,+,$chr(40),$regml(1)) | echo 4 -a $iif($chr(44) isin %r,%x,%r)
}