Get access to custom control in XsltListViewWebPart

Hello everybody.

I try to get access to control added to XsltListViewWebPart in SharePoint designer for c# server code.

First, I add new column with "Insert left" in SPD. Next, I put asp:Checkbox in created column.

<td><xsl:variable name="ID"><xsl:call-template name="ResolveId"><xsl:with-param name="thisNode" select="$thisNode" /></xsl:call-template></xsl:variable><asp:CheckBox runat="server" id="CheckBox1{$ID}{generate-id()}" /></td>

How I can get asp:CheckBox checked in server side in Click event of asp:Button by c# server code?

I find solution to get web part but have no idea to get check box((