Zircon bands +6 resist for rings, +15 nature, +15 fire, +10 shadow, +5 all resistance enchants to cloak, firebane cloak for +5 fire, gravestone scepter for +5 shadow resist, arctic buckler for +5 frost resist, +8 frost resist to shield should be available if I remember correctly.
With combinations of all this the max resists I could get were -
Fire - 32. (firebane +5, +15 fire to cloak, 2x +6 zircon bands)
Shadow - 27. (+10 shadow to cloak, 2x +6 zircon bands, gravestone scepter)
Nature - 27. (+15 nature to cloak, 2x +6 zircon bands)
Frost - 30. (+5 all resist to cloak, 2x +6 zircon bands, arctic buckler +5, +8 to shield)
I could be missing something but afaik this is about right.