You might try a search at www.useit.com for facts to back up your point of view. I know they've addressed this issue on multiple occasions.

My question is why would the client prefer scrolling. I've had clients who thought the design phase would be cheaper with less pages and were willing to trade usability for initial costs. If this is the case with your client you'll need to make a case for a higher ROI even if the inital outlay is higher.

Good luck,

JM

http://www.crucibledesigns.com