You can position anything precisely in CE3. It works on x,y,z vectors, just like Sketchup. Larger numbers is all.
Setup your component origins so they easy to work with (center or corner).
In sketchup - Work out the vector difference (distance in x,y and z directions) between component origins
In CE3 - select first component, take note of vector (x,y,z - found somewhere between viewport and console). Add vector difference you got from Sketchup. Place second component on the resulting vector... Bam! Robert's your mother's brother.
Cheers,
Alexi