is a good place too look for mandrake specific advice - I don't know about other kernel versions, but from memory it's pretty straight forward to install differing kernel versions obtained from mandrake - i.e. the "mandrakised" ones.
Have you, by chance checked the mirror's? I'd see what's available myself, by going to easy urpmi
and following the instructions to update your urpmi sources (if you haven't already done so, of course), and make sure you include all the availabe sources i.e. main, contrib and updates - oh, and I always used one from the plf as well (some of their stuff is nicer/more up to date than mandrakes stuff).
Then if there's a kernel and kernel source available, you can just do that from the mandrake control centre. VVV easy.
But if you're thinking of something from kernel.org or whatever, then the only suggestion I have is to check the mandrake forum here at LQ and the mandrakeusers one I linked earlier.
Hope this helps a little