<?if($PAGE_ID$='threadpage')?>   
<script type="text/javascript">   
function go(){   
page=$('#gopage').val(); // X-3me ~  http://x-3me.ru   
ftid=location.href.split('/')[4];   
fid=ftid.split('-')[0];   
tid=ftid.split('-')[1];   
document.location.assign('/forum/'+fid+'-'+tid+'-'+page);   
}   
</script>   
<form>   
На страницу:      
<input id="gopage" type="text">      
<input value="Перейти" onclick="go();" type="button">      
</form>   
<?endif?>