To get a man into a line, i.e. to divert his attention by a ridiculous or absurd story. To humbug.
Definition taken from The 1811 Dictionary of the Vulgar Tongue, originally by Francis Grose.
Line of the Old Author * LingoNathan Bailey's 1736 Dictionary of canting and thieving slang
John S. Farmer's collection of canting songs and slang rhymes