Upon PidginPortable install, it seemed to have automatically migrated my previous GAIMPortable profile settings over just fine. But, I typically use the Yahoo protocol the majority of the time, and I was very disappointed in the default Pidgin smiley/emote theme. And I'd become quite accustomed to the original default smileys/emotes from GAIM, which were a copy of the same default sets from the individual branded messenger programs. Since I don't like jumping through alot of hoops to add/merge smileys, and PortableApps are about simplicity anyway, I came up with this simple method to bring the originals back:
Open "C:\PortableApps\PidginPortable\App\Pidgin\pixmaps\pidgin\emotes\"
and rename the "default" folder to whatever. (I use "P_default". This step is to save the original Pidgin theme, in case you want to revert back to it later.)
In another window, open the "C:\PortableApps\GaimPortable\App\Gaim\pixmaps\gaim\smileys\" folder, copy the "default" folder, and paste it into the "C:\PortableApps\PidginPortable\App\Pidgin\pixmaps\pidgin\emotes\" folder (where you just renamed the original one).
Open up PidginPortable, you'll have the original GAIM theme set back.