You don't have to "collect" them because your existing wallet keys will work on both chains after the fork. So you simply "have" them. But, you will need to import your keys into a wallet that uses the Bitcoin Cash network in order to see and use them.

The online Trezor wallet will support the split. Details here:
https://blog.trezor.io/trezor-advisory-uasf-chain-split-fork-2f95cf2c11a0

If you use Trezor with Electrum, you will have to install electrum in two directories, and import the Trezor keys into the second install. You also have to change which server the BCC wallet looks at. Details here:
http://docs.electrum.org/en/latest/hardfork.html

It looks to me like using the Trezor online wallet would be the simplest and easiest way to get your split coins.