Can l model up a cabinet with the incontext method and then have the Length, Width and Height driven by an Excel Spreadsheet

I've modelling up a cabinet by using the incontext method with the assembly.... problem is when l create a excel spreadsheet...only one dimension can be driven from the spread sheet which is the Length of my cabinet... the height and width l have to edit the sketch in order for this to update. I want the excel spreadsheet to drive the Length, width and Height at the same time instead of me having to edit the sketch all the time... is there a method to do the sketching inorder for me to be able to the excel sheet drive my model? Please anyone l've been searching the internet but l somehow cant find a solution to this problem.

My left and right panel will be the same part.
My Top and Bottom aswell as my back and front panel will not be the same part.

Anyone, someone please put me out of this misery please.