1. Using an existing dvi file
Suppose that a page is of A4 size and is displayed by scrolling only vertically with the maximal width in the screen:
 
 - Shift the position and size of a page to cut space in the sides of a page.  For example, under Help -> Setup Parameters -> [Paper], set

-OX=-2.25cm
-OY=-2.50cm
-y=F15.80cm:21.80cmP

Save these as a mode in [REGISTRY] if necessary.
This adjustment can be automatically done by Presentation Menu->Cut edge or selcet Display -> Region -> On, define region by [Shift]+Mouse and Display -> Region -> Cut.

 - Change the settings View -> Cover sheet, Seamless HyperJump, Presentation type, Cover type if necessary.

 - To use the seamless vertical scroll, select Display -> Y-two pages (this is done by [0] key in default).

 - After moving to Presentation Mode by [ESC], display a page under Full mode (this is done by [6] key in default).

 - The function to display 4 or 16 pages at a time ([8], [9] key in default setting) may be usuful.  Then by the clicking one of the pages by the right button on the mouse, the pointed page will be displayed. 

2. Making a dvi file for Presentation
Suppose that \documentclass{slides} is chosen at the head of the LaTeX2e source file and that a page is totally displayed without a scroll.

 - Define the size of the page(\paperheight, \paperwidth) under consideration of the resolution of fonts and the screen. In particuler, the ratio of the horizontal size and the vertical size of a page should be equal to that of the screen.
Arrange the values of \hoffet, \voffet, \textwidth, \textheight.

 - Write the TeX source by using dviout specials and pause special so that Presentation will proceed in Fit mode ([5] key under the default setting) only by pushing [Space] key.