These use to be one of my go to steelhead lures, and still remains in the box.
I tend to dead drift them. Sometimes I slightly hold back just enough that the float creates a small wake.
They also work well on a light spin casting rod, cast them and nothing else (no weight, etc) into a backwater and let it sink to bottom then retrieve slow.
As for depth, when dead drifting set your gear around 1-2 feet off the bottom (typical answer). They spin quite well with just currents in the river. Indiana blades are better for dead drifting I'v heard as they catch more water, but I'v never had a problem dead drifting Colorado's and this is my go to method for them.
If holding back set you float to JUST tapping bottom every 10 seconds or so (tick here and there).
This will ensure that when holding back your Colorado will still remain 1-2 feet off the bottom (it will rise if you are holding back).
Once I get to the tail-out I tend to lock my reel and let it swing into shore (in faster runs), then start reeling. You wouldn't believe how many I have hit in the 1st 3-4 cranks.
Weight... it depends on float size.
I run a stubby float 4" with a shaved/tapered bottom. I normally run 4-5 split shots in size 4 about 1 inch apart from each other.
Leader Length.
-I use to run (and still do at time when picky) a 2-3 foot flouro leader in really high vis (6+ feet vis) conditions. I find Colorado's sink fairly well so they don't float up out of the zone unlike roe would (assuming you are not holding back on the Colorado).
-Normally a 12 to 16 inch leader will work fine.
Size of Colorado.
Steelies like size 4 I think it is (I go on sight, but it's quite large).
Coho I use both large and small, it depends on what they want that day. I like silver, gold, and dark blue.
I have also seen guys bottom bounce aka drift fish these.
a couple small weights and a 1-2 foot leader and let it tap bottom while drifting, sometimes slowly reeling in as you would a spoon.
Hope that helps,
Cheers,
Dan