in reply to
GIF to JPEG without GD/Image::Magick
You can install modules yourself, without root/admin access.
With modules such as GD (not sure about Image::Magick), you may also need to install the libraries too.
See A Guide to Installing Modules, paying specific attention to the "I don't have permission to install a module on the system!" section.
With this in mind, I'd look at installing and using Image::Magick - it works a treat.
If the information in this post is inaccurate, or just plain wrong, don't just downvote - please post explaining what's wrong.
That way everyone learns.