Can iCal scroll by week in month view?
iCal is limited to the view modes you see in the main window - Day, Week, Month and Year. It's not very customizable.

However as an alternative, you might want to look at BusyCal. It's a pretty well regarded app. The two word pitch is "iCal Pro". It integrates with the system calendar, so all the built-in calendar based functions work fine, and in addition to iCloud sync, it has much better Google Calendar sync if that's a selling point. Most importantly for you it's more customizable in terms of views, and the month view scrolls by week.

Sorry there's nothing to be done with the existing app, but BusyCal is probably the best option to get what you want. There's a 30 day demo, so give it a try.