Hello,
We have no such a web part called custom table form web part, so that would be your custom one and you can use our API to get the value from your parameter in a query string like this:
CMS.GlobalHelper.QueryHelper.GetString("param", "no parameter");
(where "param" is a name of a query string and "no parameter" is a default returned string, when the param is missing in url)
Best regards,
Jan Hermann