It turns out that 9 loops is considerably easier than 10 to manage by yourself, because the way they are held leaves a finger free for manipulating other loops. I'm going to introduce you to the tricks of managing many loops with a Moroccan braid described in Speiser 2000. (example)
1. Place 5 loops on your left hand, 2 on A, one on B, C, D left, and four on your right hand, the same but with D free.
Method A (original directions)
2a. With D right, take the back/lower loop of A left unreversed through the front/top loop.
3a. With A left reach through the loop on D right and take the loop of B left unreversed, putting it on the top position on A left. Place the loop from D right onto B left.
Method B (simpler adaptation, but doesn't help with other braids)
2b. Put the loop on B left onto A left, making three loops on A left.
3b. Take the back/bottom loop on A left unreversed through the next loop on A left, and over the top loop on A left, placing it on B left.
4. With the now-empty D right, reach through D left and C left and take the loop from B left unreversed.
5. Move the loop on C left to B left, and the loop on D left to C left.
Repeat the sequence on the other hand.
This makes two separate twill braids, since all takings are unreversed. If you want an unfoldable single braid, then take the bottom loop from A left reversed and the bottom loop from A right unreversed. Taking both reversed will make a tube. All other takings are always unreversed.
Step 3a is tricky, but essential. It took me a while to figure it out.
It's much easier with 9 instead of 10 loops because you have a finger free, but the recipes for any of the multiperson braids can be converted to one-person patterns (given enough finger dexterity). First, though, you need to figure out the structure of the braid so that you can translate it into this different way of working.
Set up 5 loops, 4 of one color and 1 of another. Place the different loop on your left index finger, and the rest as in a standard 5-loop pattern. Work the open lace pattern (both sides taken unreversed), tracking the movement of the colored loop as it travels from the left edge to the right edge. There are four possible paths it can take at each crossing: over, under, around or through. Write down the sequence that the loop follows, then track it back from the right to the left (answer below). There will be one less crossing than there are loops. This braid is symmetrical and has no reverses, but many braids are neither. Try the same exercise with another pattern. Make sure to write down the locations of any reverses, in either direction.
Once you know the unique sequence of movements a loop must follow for a particular braid structure, it is possible to work out other ways to create that structure. Try it with the open lace of 5 loops, starting with 2 loops on A left, 1 each on B, C, D left (one possible answer below).
The two-person braids involve two workers doing the same things in mirror image, then exchanging loops. You can create the same effect by working with 5 loops on your left hand, then 5 loops on your right hand, then exchanging next loops.
This is an alternate method, and might be easier on your off hand. I've marked with a * the points where switching the reversed/unreversed directions will give you different braids.
1. Take 5 bows on each hand, 2 on A, 1 each on B, C, D.
2. With D right reach through D left and C left, and take the bow from B left reversed (*).
3. Move C left to B left and D left to C left, and place the bow just taken (in step 2) onto D left.
4. Put the bow on B left onto the top of A left reversed (*).
5. Take the back bow of A left around the other two bows, and place it onto B left.
6. Repeat 2-5 on the right hand.
7. Exchange the loops on your D fingers by placing the loop from D right onto D left, then taking the back loop from D left around the front loop onto D right.
The path taken by a loop: around, around, through, through, and the same back.
1. Take 5 bows on your left hand, 2 on A, 1 each on B, C, D.
2. With D right, take the outer bow from A left around the inner bow unreversed.
3. With A left, reach through the bow on D right and take the bow from B left.
4. Place the bow from D right onto B left.
5. With D right reach through D left and C left, and take the bow from B left reversed (*).
5. Move C left to B left and D left to C left, and place the bow just taken (in step 2) onto D left.