Wife and I have separate iOS devices, separate iCloud accounts. But we both want to access mail from the iMac (OSX Mavericks.) Currently only my mail is linked. How to configure so that wife's iCloud mail can be seen on iMac. Simple and explicit please!

Go to System Preferences>Mail, Contacts and Calendars and sign in with your wife's ID. Check only 'Mail' in the checliks there unless you also want access to her contacts and calenders. Her mail account will appear as a separate account in Mail.

If Mail in Mavericks is the same as earlier versions you can select accounts in the sidebar, so that you can either display the inboxes for individual accounts, or the contents of all the account inboxes. (If the accounts don't show click the disclosure triangle next to 'INBOX'). The layout may have changed since the version I have - Snow Leopard - but you should be able to do the same thing.

Just to confirm that Mail in Mav handles this as it used to. It creates a unified inbox (and sent etc), clicking the disclosure triangle reveals both inboxes separately.

Slow and sure works :)

Join the club, I'll send you an application form, once I remember where I put them. :)