Best way to build a hot pluggable WCF service library

Assembly a = GetAssembly();
Type t = ExportModule.GetExportType(a);
if (t == null) throw new Exception("No proper type found.");

object iExportModule = Activator.CreateInstance(t);
object[] arguments = new object[] { _export.ConnectionString, GetFileName() };

t.InvokeMember("ExecuteExport", BindingFlags.Default | BindingFlags.InvokeMethod,
     null, iExportModule, arguments);