Setting a Drawing Scale

I must be missing something obvious.  I want to create a scaled drawing.  I make geologic cross sections with drill holes that are 500 to 1000' deep.  I would like to set the drawing scale to something like 1"=250'.  So a 1000 foot drill hole would be a line 4 inches long on the screen.  I have gone to the Drawing Scale List and figured out how to create a new scale, but nothing I try allows me to change the drawing scale from 1:1.  I can edit the list, but I can't change the 1:1 default.  I have tried right clicking, double clicking etc.  It seems that the drawing area stays at the original 1:1 scale.  What am I doing wrong? I want to make a drawing where I can give the Line command the coordinates 250,0 and it draws a vertical line 1 inch long.  I would appreciate any help. Thanks.