Scalaz does it as follows:

trait MA[M[_], A] {
  def value: M[A]
  def >>=(f: A => M[B])(implicit m: Monad[M]): M[B] =
    m.bind(value, f)
}

With implicit conversions from M[A] to MA[M, A] for all M[_] and A:

implicit def ma[M[_], A](m: => M[A]): MA[M, A] = new MA[M, A] {
  lazy val value = m
}

You just need a trait Monad and an instance of it for every monad you care about:

trait Monad[M[_]] {
  def pure[A](a: => A): M[A]
  def bind[A, B](m: M[A], f: A => M[B]): M[B]
}