xsl parameter to javascript

Hi

In a DataFormWebpart i want to be able to have a button that invokes javascript

I have: <xsl:value-of select="@CustomerName"/>

I want the value of CustomerName to be passed to a javascript code using a button.

<input name="BtnSelect" type="button" value="Select" onclick="javascript:PopulateParent('What do I put here');"/>

I've tried adding this button within the DataFormWebpart but it errors, 'not well formed'

Any ideas on how to achieve this?

UPDATE: The dataform webpart is displaying information from a sqlDataSource. Would it be better to grab the information from this rather that the DataFormWebpart?

<DataSources><asp:SqlDataSource id="SqlDataSource2" runat="server" __designer:commandsync="true" ProviderName="System.Data.SqlClient" ConnectionString="Data Source=spsql20104;User ID=SQLlogintest;Password=AAA123;Initial Catalog=Leads;" SelectCommand="SELECT * FROM [CustomerDetails] "/></DataSources>
<datafields>@Id,Id;@CustomerName,CustomerName;@CustomerAddress,CustomerAddress;@CustomerDOB,CustomerDOB;</datafields>

Thanks