i regularly do key runs on mp5-7 efficiently with minimal deaths.
With regards to gear setup, 1st of all it depends if you are 1h+mojo @ 2h (skorn) user. For 1h+mojo using low mana spell such as splinters@ghost bomb .. stack as much ias u can bcos u wont hv problem with mana (tal's armor + mempo + lacuni + witching hour). However if you are 2h user & Bears is your main dmg dealer ... u want minimal ias as possible (more ias = faster u run out of mana .. 0 mana = 0 dps) .. instead u want to stack on crit chance to make full use of Skorn high CHD. Bear in mind that to survive high mp & deal with RD packs u need Life Steal on your 2h wpn. Zuni full set works best with 2h setup since the +20 mana regen helps with spamming more bears.

This is my skill setup/build for mp5 and above using 2h wpn (Skorn with LS):

Left Mouse Button: Corpse Spiders/Widowmakers (mainly used for mana regen)
Right Mouse Button: Zombie Charger/Zombie Bears (main dmg dealer .. great at clearing large pack)
Keyboard 1: Spirit Walk/Honored Guest (multiple use ... mana regen, getting out of sticky situation, spam bears w/out getting dmg reflect)
Keyboard 2: Grasp of the Dead/Unbreakable Grasp (some dmg over time but main purpose is to keep mobs in one place so that its easy to hit using Bears)
Keyboard 3: Hex/Jinx (crowd control .. hexed unit get 20% more dmg ... great at killing tough elite boss @ key wardens)
Keyboard 4: Gargantuan/Bruiser (tanker + stun keep target in place to hit with Bears)
Passive 1: Vision Quest (sync with widowmaker to get 30% mana regen)
Passive 2: Spirit Vessel (2nd set of life to make sure u dont get 1-shotted)
Passive 3: Blood Ritual (spell will cost less mana so can spam Bears more)

Additional: For solo gameplay its adviseable to use Templar for 2nd Tanker (u dont need zdogs) .. equip him with Azurewrath + Star of Azkaranth amulet will enable him to freeze target most of the time (combination of Templar freeze + Garg stun .. provides u with 2 good tankers that can control mobs) .. Stormshield make him survive better . puzzle ring give more gobs (since templar is melee he get hits all the time so more chance of gob spawn from puzzle ring) .. Vitality Hellfire ring will give him huge health boost & u get xp bonus too. For relic get high vit + block chance + armor/all resist.

This build is pretty balance between survivability & damage. If u need to do speed farming for xp/gold/item on lower mp .. its better to use Gruesome Feast/Grave Injustice Combo + Soul Harvest to get huge dps boost .. Jaunt+Stalker for fastest MS .. Circle of Life+Sacrifice/Pride for free zdogs & elite killer/instant mana topup .. Acid Rain as main attack to 1-shot large group of white mobs.

I hvnt use 1h+mojo setup for quite some time now .. but if u need a good build for it .. i will equip myself with my socketed EF + mojo and try do some key runs using it .. will post a build for 1h+mojo later if need be.

Link to my Witch Doctor