I am eligible to do your task as I have considerable experience working with AutoCAD and Visual Basic. I sell software LXQCAD which deals with automatically generating longitudinal and cross section of road, canal, etc.
Your task requires a DXF reading and writing module as AutoCAD VBA is not an option. AutoCAD LT does not support VBA as far as I know. Also there are differences in DXF version.
Depending on the tasks you require, I've provided an approximate time estimate to complete the task.
I can send samples of CAD applications I've developed if you message me.
Regards,
Juby Abraham