This is possible on either side but is easier and faster on the right side. Roll to the corner of land shown in the video, getting close to the edge and close to the portal fight trigger without hitting it. LJA along the wall (not precise) and Link will bypass a spawn checkpoint before voiding. This makes Link respawn in the place he would spawn after voiding during snowboarding, which is within Yeto's cutscene trigger and immediately begins the cutscene. When done successfully, the blue arrow on the minimap will change position just before Link voids out to reflect the spawn point change.
With slow aim, the ice keese may attack before Link can draw his sword to LJA. If this happens, step back from the portal fight trigger to kill the keese, as a spin attack in place will often hit the trigger.
Skipping the portal saves 24s over completing the fight. However, it prevents the rupees from spawning on the snowboarding track on GCN, and it also prevents the fog from dispersing, leading to "Blind Snowboarding."
This trick can also be performed without a boomerang LJA by rounding up keese in the boomerang, throwing them over the void towards the wall, and jump attacking when they come back in range.
It saves 10-15s to skip the portal this way, but unlike on GCN, the rupees and keese remain loaded during blind snowboarding in the Wii version.
This method is obsoleted by the methods above, but was the first method discovered and is listed here for archival purposes. It was not deemed faster to skip the messengers when this was discovered in 2009 due to the route needing the rupees from the treetops.
In a route that leaves and then returns to Snowpeak Ruins without Ooccoo, such as the old Yeta TD 100% route, it is possible to LJA from the Snowpeak portal area all the way down to the dungeon with Map Glitch, savewarp after hitting a spawn checkpoint under the bridge, and load the save in front of the dungeon. This requires the Midna text in front of Snowpeak Ruins to have been hit already, meaning it cannot be used to get to the dungeon for the first time. This saves around 5s over snowboarding again.
It is possible to descend the snowboarding slope with LJAs and wolf movement. Although the wolf movement is slower than snowboarding, it does skip cutscenes and is a little faster if aiming to collect the poe soul on the way down.
First, LJA over the first gap. The only way to LJA in the deep snow is to not move at all after transforming human; if Link moves after transforming, the jump attack becomes impossible. All the other jumps can be made as wolf. For the first jump in the shortcut, use the rock to the left as a bridging point. The second jump in the shortcut is a little close, but dashing just before reaching the edge gives Link enough speed to clear the gap. Finally, LJA over to the poe mountain as shown in the video.