Yes, you can configure them exactly as you have mentioned, however load balancing is determined more by your infrastructure and MX records than the device config itself.
You will need to setup your MX's to point to both appliances and that can either be equal weighted (round robin) or the usual priority setup.
You can even run a third one as just the quarantine store as it doesnt really care it just takes mail on port 41025 and stores it, then users authenticate and get their mail.
Or you can use SBG vmware, or SB for SMTP etc.
cheers
Z