Surprisingly the parameters collection isn't exposed publicly so you'd have to extend the built-in AdoNetAppender and expose them:

public class AdoNetAppender2 : AdoNetAppender
{
    public AdoNetAppenderParameter[] GetParameters()
    {
        return m_parameters.Cast<AdoNetAppenderParameter>().ToArray();
    }
}

Then you can ask the repository for all the AdoNetAppender2 appenders and inspect their values:

var repository = LogManager.GetRepository();
foreach (var appender in repository.GetAppenders())
{
    var adoNetAppender = appender as AdoNetAppender2;
    if (adoNetAppender != null)
    {
        foreach (var parameter in adoNetAppender.GetParameters())
        {
            // parameter.ParameterName;
        }
    }
}