Getting in with 2 tanks is easy...
here is what I do from shore (Tulamben, large rocks, calm conditions mostly):
Shore
-check all tanks
-don wetsuit,bcd and computers
-slide fin straps through forearms
-open tanks and carry them to the water (using them as "canes" to stabilize if needed)
Shallow
-clip both tanks' top bolt snaps
-if bringing a deco tank, I'll have carried 2 and will pass them to my team mate. I'll then get out to bring my backgas
-don fins
-connect bcd Lpi hose and inflate
-put left reg in its bungee around my neck
-orientate the turret on left first stage
-connect bottom bolt snap on left tank
-pass long hose around neck and in the mouth
-clip right tank's bottom bolt snap
-put mask on
-descend to 5m
-put bungees on both sides
-do a final bubble check and descent check
-descend further
On speedboats here with outboard engines where giant strides cannot be done, I'll:
On the boat
-don wetsuit, bcd and computers
-check all tanks and open valves
-don fins
-bring left tank with me to the backroll area
-clip left tank's top bolt snap
-connect lpi and inflate bcd
-orientate first stage turret
-bungee left second stage around neck
-get the crew to give me the right tank
-clip the right tank's top bolt snap
-pass the regulator hose around neck
-put second stage in mouth
-don mask
-back/side roll with tanks in between my legs. You can push the tanks down with arms if needed.
In water
-clip left tank's bottom bolt snap
-clip right tank's bottom bolt snap
-this is where I get my deco tank from the crew and clip it on my left d-rings if needed
-descend to 5m
-put bungees on both sides
-do a final bubble check and descent check
-descend further
I also dive from small outriggers where I get in the water with no tank, obtain tanks from captain and gear in a very similar way to shore entries...