This is a very good breakdown on a Podiatrist billing Unna Boot application and why to use 29580. They also argue to not bill A6266 because Medicare will not cover the actual equipment used for the Unna Boot application:
List of all the ICD 9 codes that are covered with Unna Boot use:
http://www.medicalbillingcodings.org/2011/04/what-supplies-can-podiatrists-bill-to.html
Dynarex Unna Boot Bandage, 3 Inches X 10 Yards, 12 Count $52
Explanation you can bill an E and M code with an Unna Boot application assuming you have a separate diagnosis and treatment performed:
http://mbt35690v.livejournal.com/13722.html
You can bill for removal of the Unna Boot if it is removed by an outside practioner:
Also this explains how an Unna Boot can be billed to reduce swelling as well, not just for ulcer care
http://www.medical-billing.com/blog/tag/unna-boot/
UNNA BOOT BANDAGE W/ZINC DYN Size: 4″X10 YD $5
How to bill for Debridement and Unna Boot Application here: