Your best approach is still to install SOHO. OpenOffice is an optional component. Simply don't select it during installation and you won't get it. AbiWord, Gnumeric, and SIAG Office are all in the extra repository in SOHO so you can install them with either gslapt or slapt-get at the command line. For SIAG be sure to also install ispell if you want spell checking to work.
You can go into KDE's settings menu and select Spanish as your language. For non-KDE apps, including Gnumeric and AbiWord, you will need to set some variables to es_AR for Spanish language and Argentine locale to be set as your defaults. These can go into your .bashrc file if you want to do this on a user by user basis:
Then export all four and you should have most everything working as you want. If you want Unicode support change es_AR to es_AR.UTF8 This may cause problems with some older programs that don't yet support Unicode. If you need Unicode support let us know and I'll post a few pointers to make things like man work
For Spanish spell-checking in AbiWord you will need to install aspell-es from the testing repository. It should be moved to extra soon but it hasn't happened yet.
If you want the system-wide default language to be Argentine Spanish do the above but also change your /etc/profile.d/lang.sh and /etc/profile.d/lang.csh files. When you edit them just replace en_US with es_AR.
My apologies for writing this in English but my Spanish is extremely poor. I'm sure it would make you laugh but I'm not sure you'd get your answers clearly.