[EDIT 12.08.06] If you have firmware 2.8, you can't use this script!
step-to-step guide to install ipdf5 & ipdf4
This the latest
version 0.41 [maybe a final version]
Sorry for consistently posting a new version.

With every step I have learned something new & it were integrated in the shell scripts.
What's new:
[1] shell script is path independent.
[2] User doesn't need to choose the right firmware anymore, because shell script does it for you.
[3] v0.41: script optimization [for instance user's interaction "Click for firmware test" was removed]; ipdf5 & ipdf4 scripts got there own directionary names -> you can run both scripts in newspapers folder, therefore only one zip-file as download.
Precautions when you update from older versions 0.1-0.3
Please delete the old pdfviewers or pdf_viewers directionaries of the previous pdfviewers##.zip, then extract choosed zip file.
What do I need?
# firmware 2.7.1:
iRex's shell update iDS download [without this it won't work!] [more information
here]
# or firmware 2.7.0:
[SHELL] hack installed.
What do I have to do?
[1] Download the zip file.
[2] Connect iLiad with USB cable.
[3] Extract content of choosed zip-file to the newspapers folder of iLiad's USB drive.
[4] Disconnet iLiad USB cable ["Connected to PC..." logo is gone]. You can use the iLiad again.
[5] Press iLiad's "news" button.
[6] Click on the entry »Do you want to install ipdf5?« or »Do you want to install ipdf4?«.
[7] Green Lamp blinks. It only takes few seconds. Blinking stops. Screen get's refreshed. This it was. [no reboot needed]
Can I reinstall iRex's pdf viewer?
Yep.
[1] Press iLiad's "news" button.
[2] Click on "Do you want to reinstall iRex's pdf viewer?"
I don't like the newspapers folder. What now?
Thanks to the new feature of 0.4 you can copy the content of zip-file to any folder [USB drive, CF, & MMC], you have access to in Contentlister. I recommend to use one of the dirs of iLad's USB drive, because then you have always a easy access to it, especially if you have several memory cards.