I think you should use item template. You couldn't show more than 4 or 5 items because you have to use "Full Mode template". to use item template you should do something like this.
<toolkit:ListPicker x:Name="ListPicker" Margin="12,3,12,12" Foreground="#FF00C000" SelectionChanged="ListPicker_SelectionChanged" >
<!--Normal Item template-->
<toolkit:ListPicker.ItemTemplate>
<DataTemplate>
<TextBlock Text="{Binding}"/>
</DataTemplate>
</toolkit:ListPicker.ItemTemplate>
<!--Full Mode template-->
<toolkit:ListPicker.FullModeItemTemplate>
<DataTemplate>
<TextBlock Text="{Binding}"/>
</DataTemplate>
</toolkit:ListPicker.FullModeItemTemplate>
</toolkit:ListPicker>
To populate the listpicker you only have to use itemSource propetary
//list string
List<String> itemsList = new List<String>();
// create 100 items
for (int j = 0; j < 100; j++)
{
itemsList.Add("item" + j);
}
//itemsource
this.ListPicker.ItemsSource = itemsList;
to get the selectedItem you could do something like this
String ListPickerOperator= ((String)this.ListPicker.SelectedItem);
switch (ListPickerOperator)
{
case "item1":
MessageBox.Show("item 1 was selected");
break;
case "item2":
MessageBox.Show("item 2 was selected");
break;
/*
.
* .
* .
* .
* .
*/
}