http://dehacked.2y.net/microstorage.php/info/1213309895/Sonic%20Colors%20Test.dsm
Sorry it's been almost a week, I was planning on uploading this later on last Saturday but I've been slacking off this week haha (Been playing DNF).
So from my understanding of how this zipline glitch works, the first time it takes the difference of your x-velocity when boosting backwards and adds the difference from it and your x-velocity the next frame, then frame after that it makes that value into speed.
So for example (this isn't the exact figures from the movie), 41952 is the value that boosting sets your x-velocity when going right. Boosting left makes it temporarily -41952. The difference is 98304. Add that to the speed value of 41952. Adding that with 98304 makes the value 140256. That becomes the new value for speed. When performing the glitch a second time, the difference is added to the speed value again. So 140256 + 98304 = 238560.
Formula: (X + -Y) + Z = S
X represents x-velo right
Y represents x-velo when boosting left
Z represents speed
S represents New speed
The glitch can't be used right after getting on a zipline. Y-velo has to be 0 and depending on the x-velo prior to getting on the zipline, it takes 1-3 frames until it becomes 0.
Last note I'd like to add is that this formula completely break when hitting a zipline with an excess x-velocity (65792 for example). The results are completely different and there's a LESS of a boost in the speed value.
Nitsuja gave a great description of how speed and x-velocity works. Basically Speed value is possible speed. If it is higher than x-velocity, then upon landing x-velocity will become whatever Speed's value is. X-velocity is "Actual speed" and that is how fast you're moving each frame. So that's why moving so fast doesn't occur until after landing from the zipline.
The reason I didn't building up any extra speed, or even actually use, the second zipline is for a plethora of reasons. For one, x-velocity goes back down to regular values of 41952 (boost) or 40960 (non-boost). Too much time is lost setting it up. A lot of time is lost due to having to having to use the launch at the end of the zipline to get the launch. There's waaay too much speed (There's an oxymoron for a Sonic game) is gained going onto the rail. It makes it impossible to land atop the loop, wasting more time. It's still possible to glitch the breakable wall into not loading. However x-velocity has to be dropped down quickly in order to make it under the wall with spikes on top of it. Then to top it all off, all the extra speed and x-velo is lost after reaching the loop. Overall it's not worth using the second zipline at all.
Incase anyone is wondering, the ziplines aren't worth doing this glitch on Tropical Resort 1 for a big reason. Every area where there is a zipline, there is something that makes the boost in speed lost shortly after. There is one of those walls that transports your downward (the mouth thing) at the first zipline in the level. Then for the second zipline, homing attacking up to the second zipline loses all of the gained speed. Going down early would be a possibility if it weren't for the need to hit ground to get x-velo to copy speed's value. Using it on the third zipline actually has two reasons. The curved rail forces x-velo down, losing all of the extra speed. The other big reason is that even if you skip the rail until it's evened out again, the breakable walls lose all of the speed+x-velo.
Anyways, I'm going to spend today trying to sync up the rest of the run with this improvement.