Add a new Sitecore Desktop shortcut with Sitecore PowerShell Extensions.

New-DesktopShortcut.ps1

class DesktopLink {
    [string]$DatabaseName
    [string]$Path
    [string]$Icon
    [string]$Header
    [string]$Language
    
    [string]ToString(){
        $fields = @()
        $fields += [System.Web.HttpUtility]::UrlEncode($this.DatabaseName)
        $fields += [System.Web.HttpUtility]::UrlEncode($this.Path.ToString())
        $fields += [System.Web.HttpUtility]::UrlEncode($this.Header)
        $fields += [System.Web.HttpUtility]::UrlEncode($this.Language)
        $fields += [System.Web.HttpUtility]::UrlEncode($this.Icon)
        # master^%7b66FD3C09-517C-4691-82AF-E300AC6BA329%7d^MyConcentra    en^Office%2f32x32%2fhome.png
        return ("{0}^{1}^{2}`t{3}^{4}" -f $fields)
    }
}

function New-DesktopShortcut {
    param(
        [Sitecore.Security.Accounts.User]$User,
        [item]$Item
    )
    
    $registryKey = "/$($user.Name)/Desktop/Links"
    $rawLinks = [Sitecore.Web.UI.HtmlControls.Registry]::GetString($registryKey)
    $desktopLinks = $rawLinks.split("|")
    $desktopLink = [DesktopLink]::new()
    $desktopLink.DatabaseName = $Item.Database.Name
    $desktopLink.Path = $Item.ID
    $desktopLink.Icon = $Item.Appearance.Icon
    $desktopLink.Header = $Item.DisplayName
    $desktopLink.Language = $Item.Language.Name
    $desktopLinks += $desktopLink.ToString()
    
    #$profileData[$registryKey] = $desktopLinks -join "|"
    $rawLinks = $desktopLinks -join "|"
    [Sitecore.Web.UI.HtmlControls.Registry]::SetString($registryKey, $rawLinks)
}

function Get-DesktopShortcut {
    param(
        [Sitecore.Security.Accounts.User]$User
    )
    
    $registryKey = "/$($user.Name)/Desktop/Links"
    $rawLinks = [Sitecore.Web.UI.HtmlControls.Registry]::GetString($registryKey)
    $desktopLinks = $rawLinks.split("|")
    $desktopLinks
}

$user = Get-User -Id sitecore\admin
$item = Get-Item -Path "master:" -ID "{110D559F-DEA5-42EA-9C1C-8A5DF7E70EF9}"
New-DesktopShortcut -User $user -Item $item
Get-DesktopShortcut -User $user