What you need to do is to contact the gateways on bitshares, such as openledger, crytobridge, gdex, winex, hellobts, btsabc, etc..

How to do it?

it's possible. I believe many new coins, including ERC20 tokens are impending as smart coins, but there are also many 3rd party OpenLedger type listings for many ERC20 tokens.

I would want to know if it possible to list an ERC20 token on bitshares decentralized exchange.
Thank you.