Redoing the spell slots is not a problem. Add 4 to the spell slot levels. Quite a few of which will only be attainable by Epic level characters. My Artificer's Handbook is in the other room and I am lazy right now.

I will extrapolate what the spell slot use will be.
Mass Heal: 10 - 13th level spell slots
Greater Dispel Magic: 11 - 10th level spell slots
Restoration: 12 - 8th level spell slots
Divine Favor: 19 - 5th level spell slots (Though, since it is a personal spell, it should probably be 23 - 5th level spell slots.
Domain spell slots would really only be applicable if you had those spells available in your domain. The spells must be cast each day that the item is created. In this case, a cleric trying to make this solo is going to have to have access to all those spell slots every day.
In this case, I would expect that the cleric would memorize a quickened Divine Favor in 5th, 6th, and 7th level slots, a quickened Restoration in 8th and 9th level slots, a Greater Dispel Magic in 10th, 11th, and 12th level slots and a Quickened Mass Heal in 13th+ level slots. So, this cleric will have also spent feats bumping up his max spell level
More likely, this would be a small group of Epic level clerics working together to create an Epic level item.
OK, time to stop being lazy. Let me see what the eyeball on the time period to create it will be.
Mass Heal = 380 hours
Greater Dispel Magic = 330 Hours
Restoration = 180 hours
Divine Favor = 361 hours
Total of 1251 hours or 157 days (at 8 hours a day)
That is a sizable investment of time. There are no explicit extensions to the Artificer's Handbook to handle Epic level items. It is easy to extrapolate them (as I have done), but the inclusion of a few feats to bring down the time constraints would be nice. After all, by the ELH, this item will probably only take 100 days to create at a 1,000,000 gp Market Value.
I won't comment on the likelihood of a given cleric taking the time to create this item for resale because that is entirely game oriented. Whatever rationale works best for your game is what you should use.

The same goes for item creation rules. In my case, I think the Artificer's Handbook gives me different options than I would have looked at otherwise and I am pleased with the results.
Threads to check out. (A search turns up 42 threads with Artificers in the content. I will post the 2 relelvant ones I remember posting in.

) I think we are probably starting to get off topic, so I would suggest that if we want to continue the discussion, we should make a new topic and be a bit more general. This is a cool item and somebody else might want to scope it out later without having to wade into a discussion on the item creation rules.
http://www.enworld.org/forums/showthread.php?t=60888
http://www.enworld.org/forums/showthread.php?t=63558