Problem with scaling 3d-stereo

i try to adaptate my 3d-vuzualization program to 3d-stereo support.

i try this

i read 3d-model from *.mesh file.

i can rotate model, move and scale.

but how a must calculate EYE_X, EYE_Z and FOCUS_Z ?

i can find the value of variables manually for each static scene. but how i must calculate this variables automatic for diffren-size models, with diffrent scale?

“gluLookAt( EYE_X,0, EYE_Z,0,0, FOCUS_Z ,0,1,0);”