[LiveWire]

k heres how

notice on the side bar there is a 'size to' button with x/y/z input boxes before it
and a button before the three value boxes, with '>' on it...

the '>' button assigns the value boxes the size of the currently selected object.

try this:

.turn on Grid Snaping
.Make a box that is the size you want your model
.click the '>' button before the 'size to' values,( notice how the values change. )
.delete the box
.open/import your model and select it
.click on the 'size to' button

Philip