Ok, I installed debinstall, but all it does is to add the dpkg option to the UI - I was working from the terminal anyway, so no banana

dpkg -i libsms-utils0_0.5.17.3+0m7_armel-mod.deb still fails with the same output:

Aegis rejecting libsms-utils0_0.5.17.3+0m7_armel-mod.deb: package 'libsms-utils0' already installed from 'com.nokia.maemo' -- not replacing it from unknown origin
aegis aborting dpkg -- all listed package files rejected
Compilation failed in require.

It does not want to replace the already installed version. My guess is that this was what aegis-hack is for.

Edit: As coderus re-uploaded the aegis hack, I finally able to get the fixed libsms in place. Now waiting for someone to send me a bloody emoji...

Thanks guys!

So the process is now:
1. Download the aegis hack from http://talk.maemo.org/showthread.php?t=90750 and install it using dpkg -i
2. Download the original and fixed libsms from https://talk.maemo.org/showthread.php?t=94027&page=14
3. Install the fixed libsms via aegis-dpkg -i