Changing selected index in a datalist in master page from other pages

I have the following code in a master page to build a simple navigation menu:
<ul id="nav">
<li>
<asp:HyperLink ID="homeLink" runat="server" NavigateUrl='/default.aspx' Text='Home' title='aaaaa'></asp:HyperLink></li>
<asp:SiteMapDataSource ID="myDataSource" runat="server" ShowStartingNode="false" />
<asp:DataList runat="server" ID="menuNav" DataSourceID="myDataSource" RepeatDirection="Horizontal"
RepeatLayout="Flow">

<ItemTemplate>
<li>
<asp:HyperLink ID="HyperLink1" runat="server" NavigateUrl='<%# Eval("url") %>'
Text='<%# Eval("Title") %>'></asp:HyperLink>
</li>
</ItemTemplate>
<SelectedItemTemplate>
<li>
<asp:HyperLink ID="HyperLink1" runat="server" NavigateUrl='<%# Eval("title") %>'
Text='<%# Eval("Title") %>' class="active"></asp:HyperLink>
...