Hi there,
I haven't done this for quite some time.
But as far as I remember you can use smitty to uninstall the old client and then use smitty to install the new client ... This should do the trick ...
Afterwards check if the /etc/inittab (or wherever you start the client) and dsm.opt / dsm.sys entries are still correct, run dsmc -> q fi (maybe you'll have to reenter the password for your client admin at this point) and if this works everything should be fine ...
But backup the ../baclient/bin/ or ../api/bin/ directory or wherever your dsm.opt and dsm.sys files are stored in case anything happens to them (Which never was the case when we uninstalled a client ... But it's better to have stored these files in a save place).
Regards
Thomas