I created a tutorial level that does something similar. It's very 'terse', since I have to use the SixAxis to enter text, but you should get the idea.
If you do a Text Search for flevine100, you should see a 'random endless scroller tutorial' level. Go ahead and copy that and read the notes in the level. It has a very rudimentary endless train of randomly generated blocks. With a little imagination you can see how this would work in a 'real' level.
Mine uses the random number generator, but a sequencer should work well too.
Here's a brief description of how I did it:
The key is having 2 speeds.. one to let the piece 'catch up' to the train, and one that will move at the speed of the train. You need a contact sensor to detect when you're touching the train, and when you're not. This allows your emitters to be less precise when it comes to timing, since the newly generated emitter will travel faster to catch up to the train, but as soon as it touches the train it will change speeds to match the rest of the pieces. Each block also has a destroyer attached to a tag sensor. Place a colored tag off the edge of the screen where you want the pieces to disappear.
I created a single circuit board that contained all of this logic, so it was easy to copy the logic to each of the blocks. The circuit board is given as a prize in the level if you go into play mode.
Hope this helps.
Best Answer
I'm not sure what the value is for Little Big planet 2 but in the first game you had to finish a certain number of single player levels to unlock online play.
I think this is basically to make sure everyone playing is at a reasonable standard when they start playing with other players so that games flow better rather than waiting for a player who doesn't understand how to get past a certain obstacle.