let's have a try... hmmm, if i understand your problem correctly...
The pixel dimensions for the List Columns (they are a sub-branch of Areas within Theme Studio). I tried copying and pasting the default 'slices' (which are automatically generated from the existing Background) however, they are not distinctly seperate from the Background element i.e. they are not slices. I can't find a way of copying them into PhotoShop and then getting their dimensions that way.
---> have you tried using the mask?
---> double clicking it usually opens the bmp file on the photoshop by default... or you can also try saving that theme first (after saving one of the component list columns you want to pattern your work on), then go to where you installed the theme studio (by defalt it's: C:\Program Files\Theme Studio\data\skindir\"name of your theme")... once there, open that image file you want to modify... just layer over the old one...
How to actually create, size etc. alternative Volume Setting slices...i cant work it out from the dimensions given; also, what is the design aid for in this instance?
---> use the same procedure as above...
---> rarely use the design aid... just aids you in visualizing certain ranges on the bmp image where a mask sould be placed or where an image would/should appear... waste of time... just layer on the previous/ready made images that came with the program and use them as your design aids... it's faster and easier... just don't resize the canvass or move the image as it may disorient the whole thing
hope i understood and addressed your question in some little way... still have little experience with theming compared to other themers here...
waiting for clarifications... till then...