... selct a vertex, in the modifiers tab you get a little snap tool, you can select multiple vertexes, enter a number in modifiers snap thingy, (the number = the area it will snap the vertexes in) and then they all fly to one point... other way is to select 1 vertex, check the manual snap tool, drag that vertex to other vertexes untill a cross appears, and let go..
i dont know exact name of the tool, but it has 2 options in it... selection and something else (been long since ive used max :s)