Update installation instructions for Copilot CLI (#58928)

Co-authored-by: hubwriter <hubwriter@github.com>

content/copilot/how-tos/set-up/install-copilot-cli.md

@@ -26,20 +26,94 @@ To find out about {% data variables.copilot.copilot_cli_short %} before you inst
 
 ## Prerequisites
 
-* **A {% data variables.product.prodname_copilot %} subscription**. See [Copilot plans](https://github.com/features/copilot/plans?ref_product=copilot&ref_type=engagement&ref_style=text).
+* **An active {% data variables.product.prodname_copilot %} subscription**. See [{% data variables.product.prodname_copilot_short %} plans](https://github.com/features/copilot/plans?ref_product=copilot&ref_type=engagement&ref_style=text).
-* **Node.js** version 22 or later
+* (On Windows) **PowerShell** v6 or higher
-* **npm** version 10 or later
 
 If you have access to {% data variables.product.prodname_copilot %} via your organization or enterprise, you cannot use {% data variables.copilot.copilot_cli_short %} if your organization owner or enterprise administrator has disabled it in the organization or enterprise settings. See [AUTOTITLE](/copilot/managing-copilot/managing-github-copilot-in-your-organization/managing-github-copilot-features-in-your-organization/managing-policies-for-copilot-in-your-organization).
 
 ## Installing or updating {% data variables.copilot.copilot_cli_short %}
 
-Run the following command to install or update {% data variables.copilot.copilot_cli_short %}.
+You can install {% data variables.copilot.copilot_cli_short %} using WinGet (Windows), Homebrew (macOS and Linux), npm (all platforms), or an install script (macOS and Linux).
+
+### Installing with WinGet (Windows)
+
+```powershell copy
+winget install GitHub.Copilot
+```
+
+To install the prerelease version:
+
+```powershell copy
+winget install GitHub.Copilot.Prerelease
+```
+
+### Installing with Homebrew (macOS and Linux)
+
+```shell copy
+brew install copilot-cli
+```
+
+To install the prerelease version:
+
+```shell copy
+brew install copilot-cli@prerelease
+```
+
+### Installing with npm (all platforms, requires Node.js 22+)
 
 ```shell copy
 npm install -g @github/copilot
 ```
 
+To install the prerelease version:
+
+```shell copy
+npm install -g @github/copilot@prerelease
+```
+
+### Installing with the install script (macOS and Linux)
+
+```shell copy
+curl -fsSL https://gh.io/copilot-install | bash
+```
+
+Or:
+
+```shell copy
+wget -qO- https://gh.io/copilot-install | bash
+```
+
+To run as root and install to `/usr/local/bin`, use `| sudo bash`.
+
+To install to a custom directory, set the `PREFIX` environment variable. It defaults to `/usr/local` when run as root or `$HOME/.local` when run as a non-root user.
+
+To install a specific version, set the `VERSION` environment variable. It defaults to the latest version.
+
+For example, to install version `v0.0.369` to a custom directory:
+
+```shell copy
+curl -fsSL https://gh.io/copilot-install | VERSION="v0.0.369" PREFIX="$HOME/custom" bash
+```
+
+### Download from {% data variables.product.prodname_dotcom_the_website %}
+
+You can download the executables directly from [the `copilot-cli` repository](https://github.com/github/copilot-cli/releases/).
+
+Download the executable for your platform, unpack it, and run.
+
+## Authenticating with {% data variables.copilot.copilot_cli_short %}
+
+On first launch, if you're not currently logged in to {% data variables.product.github %}, you'll be prompted to use the `/login` slash command. Enter this command and follow the on-screen instructions to authenticate.
+
+### Authenticating with a {% data variables.product.pat_generic %}
+
+You can also authenticate using a {% data variables.product.pat_v2 %} with the "{% data variables.product.prodname_copilot_short %} Requests" permission enabled.
+
+1. Visit [{% data variables.product.pat_v2_caps_plural %}](https://github.com/settings/personal-access-tokens/new).
+1. Under "Permissions," click **Add permissions** and select **{% data variables.product.prodname_copilot_short %} Requests**.
+1. Click **Generate token**.
+1. Add the token to your environment using the `GH_TOKEN` or `GITHUB_TOKEN` environment variable (in order of precedence).
+
 ## Next steps
 
 You can now use {% data variables.product.prodname_copilot_short %} from the command line. See [AUTOTITLE](/copilot/how-tos/use-copilot-agents/use-copilot-cli).