Interesting question, but it might be really difficult thing to do for a few reasons:

I'm assuming you want to use the stuff because it has a really low carb and therefor starch contents. (it's pretty much 97% water and some fiber). Sushi rice has a really high starch content which togther with the vinegar and sugar help bind everything as you'd want from sushi rice. Most binding agents you'd want to use to create a similar effect are also one form of starch or another.

Even if you want to use something like that, you're still trying to loosly bind together little pellets of already "geletanised" water. That's a difficult thing to do no matter what. Anything you do will probably interfere with the rice itself, either breaking the binding in the rice or turning everything into one big sticky blob.

That being said, if you dont mind trying some things and introducing some starch to bind things, there are a few things I would try in this situation:

Sushi rice is usually served cold, if this is the case you can try to use this to your advantage. I would try a really small amount of agar agar or maybe even pectin. These only really start binding when cooled down. In this case I somehow feel a small amount of liquid pectin (and vinegar and some sugar) just after cooking the rice, might give an interesting effect when it's all cooled down.

Otherwise I'd try introducing back in some starch, preferably sushi starch so simulate back the starch that would otherwise leak out of the rice during cooking.

Hope this helps a bit