Calling nlapiScheduleScript() from client side script

Hi All,

I have a custom record.  I have a client side script to execute a function( function depoyed by clicking Customize-->Custom Code-->Script File).  Since it has to load bulk data, it is giving a time out error.  So I decided to use a Scheduled Script.  I used a scheduled script by calling the nlapiScheduledScript(). But the script gave me an error saying:

nlapiScheduledScript is not defined
    nlapiScheduleScript('customscript_load_related_items','customdeploy1',params);

Does it mean to say that we cant use a nlapiScheduledScript() from a client side script.  If we cannot use, then what is the suggested method to overcome the time out error.  But I want the loading to happen only on clicking a button in the custom record.