On those old Mandrake versions it's very easy: just install Linux. For SuSE versions of similar age and up to SuSE 8.2 there are detailed instructions at http://volker.dnsalias.net/linux/speechrec.html. Much of these instructions would apply to other distributions too. The same page also contains other useful information and links. Some additional information may also be on http://taint.org/wk/ViaVoiceModernLinux.
To overcome problems with binary incompatibility in shared libraries, Carlo Wood has produced a script which creates a separate binary library environment for ViaVoice to run in. It may help some people, but others report that it isn't necessary. The script is now here: http://www.xs4all.nl/~carlo17/vvinstall.
People reported in the second half of 2004 that making ViaVoice work on SuSE 9.1, Mandrake (?), and gentoo, is possible with few problems and few tweaks. That it runs on SuSE 9.1 means it works on a 2.6 kernel in principle.
A number of problems with getting it to work remain and not all have been solved. The best bet is to ask on the xvoice-user mailing list (see section 9).
[ This section needs to get much bigger. Please send me questions, and if you have, answers. ]