Code:
alias mix {
  if ($0 < 2) {
    echo -abc info * /mix: Insufficient parameters
    return
  }
  if ($gettok($1,1,45) !isnum 0-15) || ($gettok($1,2,45) !isnum 0-15) { 
    echo -abc info * /mix: Invalid parameters
    return
  }
  var %colour1 = $base($gettok($1,1,45),10,10,2), %colour2 = $base($gettok($1,2,45),10,10,2), %ctoken = 1, %token, %result
  while ($gettok($2-,%ctoken,32)) {
    %token = $v1
    if (2 \\ %ctoken) { %result = $+(%result $chr(3),%colour1,%token,$chr(3)) }
    else { %result = $+(%result $chr(3),%colour2,%token,$chr(3)) }
    inc %ctoken
  }
  echo -a %result
}


This loops through each token using an iterator variable (%ctoken). With each iteration, it checks if %ctoken is not a multiple of (\\) 2, and if so it colours it the first colour you specify, otherwise it colours it the second colour you specify.