These are the two Iris 1 jetslides. The second one is the easy one but since it consumes a fair amount of flugel energy, you'll end up with about 3 or so bars left for Iris 3. Thus, depending on your Iris 3 strat, you may need to reroute how you fly it (or forgo flying entirely).
Now, the first slide... Woo boy. Getting the slide itself isn't hard, and even if you mess it up you'll usually land safely on the platform (though if you descend too early then you do put yourself at risk of colliding with the laser). The followup is what makes this trick very difficult, and in my opinion, the most terrifying trick to perform in this entire game that I currently know of. You need to slide to the eggmet, swap 5 times to the left (or 6 to the right), freeze it, continue sliding, swap one to the right, continue sliding, time slow, continue sliding... It's the combination of all of this at once which makes this so difficult to do. If you could time slow while sliding then it would be slightly easier, but the fact that you need to be standing to do it just makes it all the more annoying to execute, especially because if you mess up your continuous slides while directly over a laser, this pretty much always results in an instant death. In theory you can time slow immediately after freezing the eggmet (that is to say, have no slides between the two weapon usages), but this puts you at risk of colliding with floor directly above the eggmet, and this will result in your jetslide speed resetting to normal.
As for the Schirach jetslide, I'll try to get a video up soon. I tried getting a replay of it a few times but I kept failing the followup. I'll try to describe it though: in the first quake met room, fly at the start normally but instead of getting off of it to start sliding after the first missile firing eggmet, keep flying and descend a bit. Weave through the two time bombs in front of you and jetslide on the long platform directly in front of you. The missile barrage here has the same pattern everytime, so quickly swap to eisschwert and freeze the one missile directly in front of you when you get to it, then continue sliding until the end.