It is on SDEX, so should be able open a trustline from every Stellar wallet or exchange.
Just go to account settings, then Stellar network, where you can open/close trustline to any Stellar asset.
The fact that StellarX doesn't list it on their main page, has to do with not enough trading volume.
Later when Tagcoin will be used more, the trading volume will go up and it will appear in the "first" page.
Now you can just search for the Asset as well.