Step 1) Obtain any pair of Active wings. Dragon, Valkyrie, Obsidian, and such; NOT 1st Gen. Those make you soar rather than fly.
Step 2) Find and access a major glitch that allows your character to walk on air.
Step 3) Run/walk on the glitched air while wearing your moving wings.
Step 4) Screenshot your character the moment your wings go up.
Step 5) Tah-dah, now you know how to fly on spiralknights.
To make it even better, you can try taking multiple screenies of the wings while it's moving up/down; then loop these pictures/images into a stop-motion performance of spiral knight flying.
Here's an example:
http://tinypic.com/m/hvuxbk/2
Oh, sing this while looking at the picture to understand it better:
"I believe I can Fly, I believe I can touch the sky~
In my heart, night and day,
I spread my volcanic wings and fly away~
I believe I can soar,
You see me running to an endless doooor~
I believe I Can Fly~
I believe.
I believe I can fly~
Ooh, I believe I can flyyy"
Instructions aren't 100% clear, but still, nice discovery ^.^
"I can fly, I'm proud that I can fly~"