I finally managed to install the 2.4.23-xfs kernel next to my 4.2.18-xfs kernel thanx to a lot of help by you guys and the 'very verbose tutorial' at
http://www.osnews.com/story.php?news_id=2949
It does leave me with some strange problems I can't find an answer for. The kernel boots but during boot I get quite some errors. One of them is about iptables and the rest is about modules that can't be found. Strange since I build the new kernel without modules. Just compiled the things I needed into the kernel. So question is, does the kernel still use the old module config or something? Doesn't a new one be created during compile? If not, how can people use two kernels completely working if the kernels are differently compiled? Final question how do I get this fixed? What files need to be changed and how?
Lot of questions about the kernel again, sorry!