C# – WPF: How to pass whole Control as CommandParameter via XAML

I'm using MVVM and custom ICommand objects are provided by ViewModel layer. One ViewModel object at the same time can be attached via DataContext property to many View objects (windows, pages, etc). In ICommand.CanExecute() I want to check absence of validation errors for some controls in View (which attached to ViewModel props, significant for a particular VM command). One ViewModel can provide many commands, each of them has own set of controls for errors validation verification. So, pseudo-XAML is:

<Button.CommandParameter>
    <x:Array Type="sys_win:DependencyObject">
        <sys_win:DependencyObject>
            <reference_to_textbox_or_other_control/>
        </sys_win:DependencyObject>
        <sys_win:DependencyObject>
            <reference_to_textbox_or_other_control/>
        </sys_win:DependencyObject>
    </x:Array>
</Button.CommandParameter>

The second problem is that the particular command may be invoked by control, which itself is the part of the DataTemplate for collection item (in my case – part of ListBoxItem data template). My templated listbox item has two text boxes (binded to two props of corresponding ViewModel) and button, which invoke the ViewModel command. So, in command CanExecute() I need to check for validation errors for some window controls & two text boxes, which belongs to this listitem, not other items. The code below works fine if I want to pass ListBoxItem.IsSelected property as CommandParameter:

<Button DataContext="{Binding}" 
        Command="{Binding Path=SwitchCommand}"
        CommandParameter="{Binding Path=IsSelected, RelativeSource={
                                   RelativeSource
                                   Mode=FindAncestor,
                                   AncestorType={x:Type ListBoxItem}}}"/>

But how can I pass whole (DependencyObject)ListBoxItem as the CommandParameter? And how this ListBoxItem, passed via {Binding RelativeSource} can be mixed with other current window controls in the first code example?

I'm very sorry, but how can I add the references to controls in xaml?

<Button.CommandParameter>
    <x:Array Type="sys_win:DependencyObject">
        <sys_win:DependencyObject>
            <reference_to_textbox_or_other_control/>
        </sys_win:DependencyObject>
        <sys_win:DependencyObject>
            <reference_to_textbox_or_other_control/>
        </sys_win:DependencyObject>
    </x:Array>
</Button.CommandParameter>