It is possible using query string and section access. Assuming you are aware of your section access (else pelase refer qlikview help), add section access with the company name as userid. All your need to trigger in the button in the below url:
qvp://qlikviewserverip/demodoc.qvw?userid=<username can be parsed>
Only thing is that you need to allow access thru IE plugin in your server and your users should install qlikview plugin.