Well, you have to keep in mind that DACUS's done this way have a different range than the normal ones, but it's about the same as Falco's when he does it this way, so not too bad, but not great. If done incorrectly, it goes about the distance of Mario's, meaning absolutely nowhere...
I might be able to get Alus to upload a video of it I guess, but it's nothing spectacular, or even hard to do. Just go into training mode, keep trying until you can do it with Diddy (His seems to be the most useful so far, and the easiest to see if you did it right with), and when you can, do the same thing with Kirby.
Here's how to do it:
1) Random Move... For example Fair, right before you land
2) You land while the animation hasnt end
3) You should now be in the Fair Landing Lag Animation
4) Here you press Analog Stick Forward + C-Up ONCE and at the same time/frame (That means you dont hold the analog stick)
5) Now you mash C-Up
If you dont do Step 5, you should do an DA as soon as possible (After the landing lag of the fair)
You could try this first to get it like 50% consistent.
After you got this just do Step 5.
At least it worked for me, hopefully I could help ^^
This works the same way for moves, spotdodges, shield drops, etc. Anything with buffer frames works.