swap image men 2 på en gang

jeg bruger et js som virker helt fint men nu skal jeg bare have 2 billeder skiftet i stedet for det ene .

skriptet:
<!--
<!--
function MM_swapImgRestore() { //v3.0
  var i,x,a=document.MM_sr; for(i=0;a&&i<a.length&&(x=a[i])&&x.oSrc;i++) x.src=x.oSrc;
}

function MM_preloadImages() { //v3.0
  var d=document; if(d.images){ if(!d.MM_p) d.MM_p=new Array();
    var i,j=d.MM_p.length,a=MM_preloadImages.arguments; for(i=0; i<a.length; i++)
    if (a[i].indexOf("#")!=0){ d.MM_p[j]=new Image; d.MM_p[j++].src=a[i];}}
}

function MM_findObj(n, d) { //v3.0
  var p,i,x;  if(!d) d=document; if((p=n.indexOf("?"))>0&&parent.frames.length) {
    d=parent.frames[n.substring(p+1)].document; n=n.substring(0,p);}
  if(!(x=d[n])&&d.all) x=d.all[n]; for (i=0;!x&&i<d.forms.length;i++) x=d.forms[i][n];
  for(i=0;!x&&d.layers&&i<d.layers.length;i++) x=MM_findObj(n,d.layers[i].document); return x;
}

function MM_swapImage() { //v3.0
  var i,j=0,x,a=MM_swapImage.arguments; document.MM_sr=new Array; for(i=0;i<(a.length-2);i+=3)
  if ((x=MM_findObj(a[i]))!=null){document.MM_sr[j++]=x; if(!x.oSrc) x.oSrc=x.src; x.src=a[i+2];}
}

//-->
//image swapper

pic=new Array()
    pic[0]=" "
    pic[1]="gfx/bag_1.jpg"
    pic[2]="gfx/bag_2.jpg"
    pic[3]="gfx/bag_3.jpg"
    pic[4]="gfx/bag_4.jpg"
        pic[5]="gfx/bag_5.jpg"
        pic[6]="gfx/bag_6.jpg"
if (document.images) {
    mainpic=new Image(350,227); mainpic.src="gfx/load.gif"  //**change if move gif
    }

function changepic(newpicnum) {
    document.mainpic.src="gfx/load.gif"  //**be sure to change this if move the gif file
    document.mainpic.src=pic[newpicnum]
    } // end function//-->


takx