new part using template with dimension entry

We are trying to standardize how common parts are modeled.  We have a simple part that we have created a Part Template for which works well but we would like a box to pop up when you create a new part (using that template).  This box would allow you to input the desired dimension of that part.  I would imagine a macro to run at the time of open would work but I do not know how to write macros.

SolidworksParts And Features