Neither of those are currently possible. I created an issue some time ago for installing extensions via the command line, be sure to give it a +1 to show your interest.
Update
The recommended way of doing this is through workspace recommended extensions, this is a .vscode/extensions.json
in your project that will prompt the user to install them when they first open the folder, the file looks like this:
{
"recommendations": [
"eg2.tslint",
"dbaeumer.vscode-eslint",
"msjsdiag.debugger-for-chrome"
]
}
You can also try setting up a bash/bat script or some other automation to directly install the extensions using the CLI as suggested by parsley72 in the other answer. You will likely annoy users by doing this though, unless this is in a personal dotfiles project or something similar.