How did Menelaus catch The Old Man in the Sea?

Idothea, daughter to Proteus, the old man of the sea, tells Menelaus how to wrestle her father and extract the means by which to return home.

She says to him:

"The moment you see that he is asleep seize him; put forth all your strength and hold him fast, for he will do his very utmost to get away from you. He will turn himself into every kind of creature that goes upon the earth."

So, Menelaus and him men wait for him to fall asleep.  Next they:

....rushed upon him with a shout and seized him; on which he began at once with his old tricks, and changed himself first into a lion with a great mane; then all of a sudden he became a dragon, a leopard, a wild boar; the next moment he was running water, and then again directly he was a tree, but we stuck to him and never lost hold, till at last the cunning old creature became distressed, and said, `Which of the gods was it, Son of Atreus, that hatched this plot with you for snaring me and seizing me against my will? What do you want?`

Menelaus wants to get back home (like Odysseus), and so he holds him until he reveals it.

The old man tells them how to leave the island (the good news), but he tells them they will have to finish their voyage, going back to Egypt (the bad news).