For long scraps, just make sure they are well scrunched (like a wrinkled leaf) individually, before combining them as filler. This improves the air flow as compared to laying it all flat, then folding. (Actually, I do this with my long filler as well.) Since I usually toss my long scraps into a gallon Zip Lock, once they've dried sufficiently, I just grab a generous fist full from the bag, and start rolling it.
For small scraps, the technique is similar to rolling a cigarette. Unlike long filler, the entire length of the cut filler cigar needs to start rolling along the same line, like the square edge of cigarette paper. To accomplish this, I use two half-strips of binder, overlaid to form a rectangle at the starting edge, with the veins aligned parallel to the length of the cigar. Beneath this, I also place a full binder strip. Once the shred is gathered into a nice trough of the half-strips, I roll the whole thing as best I can, not compressing it very much. The object is to keep the shred all within the same zipcode.
This usually ends up looking like a fat, sideways volcano, but it serves to hold all the cut filler into a tube shape. When I apply the wrapper, I compress the bulk as much as possible, since air flow will not be a problem. This can make a decent cigar, though the taste is never quite right--the blend is haphazard.
Plan B is to roll a small blunt of a single strip of wrapper. I cut the strip parallel to the veins, about midway up the wrapper, flip the bottom section to form a parallel starting edge. This is a little trickier, since often about 1/3 of the cut filler wants to fall out. It's quick and dirty, but usually results in a cheap, adequate smoke, and helps make the big bag of cut scrap go away.
Bob