I have to restore my iphone 3times when i've tried to download new themes there oh my god. just remove hightymes.org/iphone-schnapps/index.xml away from your installer before ur system loop over times exec script.
There is a manual way to add new themes to your summber board/iswitcher via WinSCP

1. Download your summerboard themes here or iswitcher here
2. extract all the zip file you will have new folder like this:
for summerboard:

on WinSCP your iphone go to folder: /var/root/Library/SummerBoard/Themes
Copy themes (the folder named themes) you like there ! Open summerboard and take the rest !
for iswitcher:

Go to folder : /var/root/Media/Themes/
Copy folder .thm there then open iswitcher chose ur new themes and take the rest ...

sigh ... this is the final round for me then ... no have to restore again lol !!
p/s: Hope this tip useful !! and sorry .. my bad english ... i'm vietnamese !!