toggle between method and source of inputs

[raffrobb]

Fellow ExcelProgrammers:

I just built a financial model that does a lookup based on management
case numbers.
Using the offset, I can currently toggle between management case1 and
management case2.

Taking it a step further, I want to be able to toggle between method
and source of inputs for a model.

In this case, I want to have the option of one of three ways to input
numbers into cell(s).

First is a lookup from a table, second is from calculation section,
third is to basically override the first two, and tell excel to allow
manual input directly into the cell or set of cells in same row.

I need help getting going in the right direction, and wondering if VBA
or formula or user form is the best approach.

I have a sample if that would help.

Thanks,
Robb