Having thought about it it's probably not them anyway. You can reach them by double clicking on your datasource in BIDS.

I think you need to look at your SSAS Server properties.

In SSMS right click on the SSAS node and go to properties and tick the box for Show Advanced (All) Properties. Here you can see ExternalCommandTimeout and ExternalConnectionTimeout, defaulted at 3600 and 60 respectively. You could try changing them.

I do think that you have a larger issue here though. If it's as slow to connect as you mentioned and you are hitting timeouts it may be time to look at your environment. Without knowing anything about what setup you have it's difficult to make suggestions other than the obvious.