For MintPPC32 users who would like to upgrade SeaLion from 32.5.0, which is installed by default, one can download it from here.
To have SeaLion 33.6.1 working one needs to install an old library (libjpeg.so.8 in /usr/lib/powerpc-linux-gnu/). It can be retrieved here.
For MintPPC64 users the upgrade goes automatically.