Hi,
You cant use ISM if there is another storage manager installed. To use ISM you would have to uninstall whichever storage manager you are using. If that is not the case then to reinitialize ISM without getting all those error messages you just need to rm all the directories under $INFORMIXDIR/ism (applogs, cores, index, logs, mm, res, tmp) and running ism_startup -init. Just remember thar if by any chance you have already a configuration with ISM you will loose it.
Luis Torres