It is not "internet explorer" (the browser). It is "Windows Explorer" (Windows file manager)
There is a great tool from PSX-Scene member aldostools called PKG ContentID 1.2 which let's you highlight a retail update.pkg in internet explorer
and press Ctrl+Shift+Enter to directly convert it to a DEX compatible package. You need to put psn_package_npdrm.exe (which isn't included but easy to find) in the same folder as PKG ContentID.
It saves a lot of time converting retail PKGs to debug PKG for DEX (3.60+ games): just a click on the update PKG then press Ctrl+Shift+Enter.
Note: The "PS3 Game Updates 2.1" can be used to download the retail PKG files to the PC
If you like multiMAN or multiAVCHD, support the development with a small donation in http://tinyurl.com/donate4MM.