Conditional Combo Box Fill

I would like to fill a combo box using a condition. That is, every cell in a
column that meets the condition, would be loaded into the box. For an
example, every cell that is a certain color. Perhaps I could use an offset
(i.e. every cell that is adjacent to a cell that has a certain character).
What I am trying to accomplish is a means to jump to an indexed area. I have
it working now, by creating the list (combo box fill range) on a separate,
hidden, worksheet. The limitation is not being able to add to the list on
the fly, and sometimes I get an error message (while scrolling the box) that
there is not enough resources to display the text. Apparently this is a
result of my box being linked to a list that is on a different worksheet.

Thanks,
Steve