I don't think so, given that it's a Barreto-Naehrig curve, not a Koblitz curve like secp256k1. It'll most likely require a new curve type to be defined.

Also, I don't know much about Ethereum, but I presume what you really want to do with the curves is more than just arithmetic operations and making signatures. In particular, I think you really want to use elliptic pairings, which definitely requires some work.

Re: documentation, I think the README is the only thing AFAIK.

It would actually be very useful for the Ethereum community to be able to use elliptic pairings in JavaScript but it is not for me at the moment. I actually just need the arithmetic operations and not the pairings.

You surely are asking yourself why I use alt_bn_128 if I don't need pairings. It's because the cost of using the alt_bn_128 curve will surely be greatly decreased because of the EIP 196 and 197 : https://eips.ethereum.org/EIPS/eip-196 and https://eips.ethereum.org/EIPS/eip-197.

Ethereum is famous and used enough to justify officially adding the curve to this library in the future.

Here is how the curve is defined:

defineCurve('bn256', {
  type: 'short',
  prime: null,
  p: '30644e72e131a029b85045b68181585d97816a916871ca8d3c208c16d87cfd47',
  a: '0',
  b: '3',
  n: '30644e72e131a029b85045b68181585d2833e84879b9709143e1f593f0000001',
  hash: hash.sha256,
  gRed: false,
  g: [
    '1',
    '2'
  ]
});

and used in https://github.com/BANKEX/BulletproofJS