[Photoshop] Is this possible with macros?

[Conrad11]

Hi there,

I wanted to know if this is possible, what I want to do is be able to:

Change a colour, press a key or click a menu item, for it to change the blending options of the selected layer based on what the colour selected is. (The layer is always exactly the same layer in exactly the same place)

I haven't a clue how to do macros properly, so is this possible?

Thanks.

EDIT:

I did have a go myself but it would only set the properties with an absolute colour when I want relative.