I got the Zimlet Proxy to open on ZD using the "openalldomains" zimlet found here:
ZCS 6.0:Zimlet Developers Guide:Examples:Open All Domains - Zimbra :: Wiki
And to deploy, just drop the ZIP in the "zimlets" directory, stop & restart ZD2.
Use the proxy test link (see instructions to figure out your port) to check proxy access...if it loads
Yahoo!, your proxy is open:
http://127.0.0.1:49503/service/proxy.../www.yahoo.com
Instructions on testing the proxy link:
ZCS 6.0:Zimlet Developers Guide:Proxy Servlet Setup - Zimbra :: Wiki
Instructions on using ZD2 in a browser, not Prism and how to deploy zimlets on ZD2:
ZCS 6.0:Zimlet Developers Guide
ev Environment Setup - Zimbra :: Wiki