With my thumbs, I have a hard time removing the barrel bushing. I bought a tool from Alchemy Custom Weaponry. Here's a video on its use:
When I got the tool, I tried it out on my Colt Combat Commander and it worked as designed. When I tried it on my Dan Wesson Valor, it didn't work. I contacted them and explained the problem. Rob shipped a new one out to me immediately. The thicker bushings on the DW's were the culprits and the new one was cut to accomodate those thicker bushings.
I recommend this tool and this company.