How to send ERC20 token to smart contract in constructor

When deploying a smart contract to a private network, how to send ERC20 token (on the same private network) in msg.value to the smart contract in constructor?

Here is the contract:

pragma ^0.7.0;

interface ERC20 {
  //standard ERC20 functions
}
contract MyContract () {
  address erc20Contract;
  uint256 value;

  constructor (address _erc20) {
    ERC20 token = ERC20(_erc20); //_erc20 is the deployed address of ERC20 token
    erc20Contract = _erc20;
    //need to transfer msg.value token to the contract
    value = msg.value; //<<==how to transfer msg.value to the contract with ERC20 function, such as token.transfer()?
  }
}