TKssrn5v8ephdmJbh7UYaUeoR4L1d4ZXds address is in base58 format, you'll need to convert it into hex format.
Using your example, you can change greet function to take an address argument.
function greet(address _address) public payable returns (uint8) {
TRC20 t = TRC20(_address);
...
You can then convert the address from base58 format to hex format using tronWeb's to hex function.
tronweb.address.toHex('TKssrn5v8ephdmJbh7UYaUeoR4L1d4ZXds')
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