its important to remember, that SketchUp only lets you print to scale, if you are in parralel projection mode.
so go to Camera > Parallel Projection. then use one of the standart views to make sure, you are aligned correctly to your model (or if your model isn't at a right angle to the original coordinate axes, right-click a face that you want to look straight onto and use the 'align-view' command).
if you now print (as Gaieus said: print as a pdf. thats ideal for furhter use in inDesign), you should be able to define the scale...
[Edit]
as far as I know the only way to export to scale, if you want to use the 'export 2d' function as opposed to the 'print' function is to export as dxf/dwg file. when you import these into inDesign, you will get the actual line work. the upside is, that you can change these lines at will (line weight, colour, etc). the downside is, that you won't get any coloured faces, textures or shadows...
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