Hi,
A couple of issues may make this challenging...
Firstly, BizTalk Server does not have a receive adapter that can poll a web service to get data. An orchestration can call a web service, but the orchestration needs to be running to do so. You may ba able to trigger an orchestration to call a service, but you will need some way of doing this.
Secondly, i seem to remember (though i may be wrong) that calling web services that return untyped DataSets. If this is the case then you may run into issued when consuming. You could test this by using one of the WCF adapters (these are better to use than the SOAP adapters) to add a reference to the service.
Regards,
ALan