como añadir esto a un archivo .JS y luego llamarlo?

[Kaopectate]

Hola xema.

Yo pondría en el js lo siguiente:

Código:

                 <script language="JavaScript1.2">

/*
Pausing updown message scroller- 
© Dynamic Drive (www.dynamicdrive.com)
For full source code, installation instructions,
Terms Of Use, visit http://www.dynamicdrive.com
*/

//configure the below five variables to change the style of the scroller
var scrollerwidth=500	
var scrollerheight=12
var scrollerbgcolor='354463'
//set below to '' if you don't wish to use a background image
var scrollerbackground='scrollerback.gif'

//configure the below variable to change the contents of the scroller
var messages=new Array()
messages[0]="<font face='verdana' size='1'><a href='http://www.stilcars-tuning.com/calendario.htm' target='_parent'>PRÓXIMAS CONCENTRACIONES</a></font>"
messages[1]="<font face='verdana' size='1'><a href='http://www.stilcars-tuning.com/calendario.htm' target='_parent' >1era Concentración Fiesta de Peñíscola 13 y 14 Septiembre</a></font>"
messages[2]="<font face='verdana' size='1'><a href='http://www.stilcars-tuning.com/calendario.htm' target='_parent'>5º MAXI TUNING SHOW Circuit Montmeló 20 y 21 Septiembre</a></font>"
messages[3]="<font face='verdana' size='1'><a href='http://www.stilcars-tuning.com/calendario.htm' target='_parent'>III GTI Tuning Du Sud en Cap d'Adge</a></font>"
messages[4]="<font face='verdana' size='1'><a href='http://www.stilcars-tuning.com/calendario.htm' target='_parent'>VI MacroConcentración RCN Tuning Salamanca 18 y 19 Octubre</a></font>"

///////Do not edit pass this line///////////////////////

var ie=document.all&&navigator.userAgent.indexOf("Opera")==-1
var dom=document.getElementById&&navigator.userAgent.indexOf("Opera")==-1

if (messages.length>2)
i=2
else
i=0

function move1(whichlayer){
tlayer=eval(whichlayer)
if (tlayer.top>0&&tlayer.top<=5){
tlayer.top=0
setTimeout("move1(tlayer)",3000)
setTimeout("move2(document.main.document.second)",3000)
return
}
if (tlayer.top>=tlayer.document.height*-1){
tlayer.top-=5
setTimeout("move1(tlayer)",50)
}
else{
tlayer.top=scrollerheight
tlayer.document.write(messages[i])
tlayer.document.close()
if (i==messages.length-1)
i=0
else
i++
}
}

function move2(whichlayer){
tlayer2=eval(whichlayer)
if (tlayer2.top>0&&tlayer2.top<=5){
tlayer2.top=0
setTimeout("move2(tlayer2)",3000)
setTimeout("move1(document.main.document.first)",3000)
return
}
if (tlayer2.top>=tlayer2.document.height*-1){
tlayer2.top-=5
setTimeout("move2(tlayer2)",50)
}
else{
tlayer2.top=scrollerheight
tlayer2.document.write(messages[i])
tlayer2.document.close()
if (i==messages.length-1)
i=0
else
i++
}
}

function move3(whichdiv){
tdiv=eval(whichdiv)
if (parseInt(tdiv.style.top)>0&&parseInt(tdiv.style.top)<=5){
tdiv.style.top=0
setTimeout("move3(tdiv)",3000)
setTimeout("move4(second2_obj)",3000)
return
}
if (parseInt(tdiv.style.top)>=tdiv.offsetHeight*-1){
tdiv.style.top=parseInt(tdiv.style.top)-5
setTimeout("move3(tdiv)",50)
}
else{
tdiv.style.top=scrollerheight
tdiv.innerHTML=messages[i]
if (i==messages.length-1)
i=0
else
i++
}
}

function move4(whichdiv){
tdiv2=eval(whichdiv)
if (parseInt(tdiv2.style.top)>0&&parseInt(tdiv2.style.top)<=5){
tdiv2.style.top=0
setTimeout("move4(tdiv2)",3000)
setTimeout("move3(first2_obj)",3000)
return
}
if (parseInt(tdiv2.style.top)>=tdiv2.offsetHeight*-1){
tdiv2.style.top=parseInt(tdiv2.style.top)-5
setTimeout("move4(second2_obj)",50)
}
else{
tdiv2.style.top=scrollerheight
tdiv2.innerHTML=messages[i]
if (i==messages.length-1)
i=0
else
i++
}
}

function startscroll(){
if (ie||dom){
first2_obj=ie? first2 : document.getElementById("first2")
second2_obj=ie? second2 : document.getElementById("second2")
move3(first2_obj)
second2_obj.style.top=scrollerheight
second2_obj.style.visibility='visible'
}
else if (document.layers){
document.main.visibility='show'
move1(document.main.document.first)
document.main.document.second.top=scrollerheight+5
document.main.document.second.visibility='show'
}
}

window.onload=startscroll

Lo demás debes dejarlo en el código original, debería funcionar.

Para mas datos de como armar tu js puedes revisar el FAQ-24.

Saludos.