Can you practice a skip cast with a baitcaster on smooth concrete of say a garage floor or the like? This is a technique I really am desperate to get down, although I'm slowly improving.

it should work , it's all about the stop and go of feathering the spool .

It won't be very realistic since no matter what you cast it will slide along fairly well on smooth concrete. In water, your bait is going to slow down or stop completely much faster. 

With water The lure will sink into water if your angle is off.

With concrete? You either smash your lure or it keeps sliding.

You could try to keep the lure at as a straight trajectory as possible with it barely touching ground.

Accuracy and consistency with low-trajectory casts are the real keys to skipping.  Simply making the bait skip doesn't do any good if you can't hit a small target area.  So while you can't practice the actual skipping part, you can practice your accuracy with the types of casts you'll be making...Which will probably help when you get out on the water.  I've been known to practice pitching and/or roll-casting into coffee cans or flower pots (or anything similar) in the back yard.  Put them on their side so can't you just plop the bait into it from above .  

 

When you get out on the water you will probably need to adjust slightly.  One good tip is to follow-through like a golfer, keep the rod tip moving toward the target and moving up...It's surprising how big of a difference that can make.  

I have been practicing skipping lately in my pool and all I have to say is it is hard and I have a ways to go.

The pitching on concrete is how I learned to skip a baitcaster. You want to have about 50-60 feet of concrete for you to learn. Instead of "skipping" it on concrete, your main practice should be to have the bait land on the concrete and slide across the concrete for 40-50feet. If you did it right, the bait will not bounce up on the concrete and just keep sliding. My recommendation is not to use a t-rigged plastic, but a hard bait (with trebles taken out) or just a lead weight (Of the approximate weight you're trying to skip out on water)

 

You're practicing how the bait should hit the water, and making sure that there isn't a birdsnest to follow.

 

Play around with settings on your reel - you'll hear anything from everything loose and no brakes to brakes and tension. I personally prefer some brakes and a little bit of tension. Some reels work better than others, depending on braking systems... It comes down to your own preferences. If you can skip a bait 20-30feet over water, you're doing well. Of course the ultimate in efficiency is to be able to pendulum the bait back without holding the bait and skipping it back out with extreme accuracy. (I'm not there yet) Keep in mind, skipping is all about placing the bait into the exact location and one perfect pitch / skip is going to be better than 10 that hit close to or around the target.

Can you practice a skip cast with a baitcaster on smooth concrete of say a garage floor or the like? This is a technique I really am desperate to get down, although I'm slowly improving.

its not ideal but a good place to start.

u want bait to slide not bounce

Just starting to skip you should turn brakes and tension up to wear you don't birdsnest when casting without your thumb...then back off with experience.

I practice in my pool