That would depend on the exact version of Forms 11g you are referring to;
is for forms 18.104.22.168 and indicates database 10.2.0.4 is certified with this version of forms. For other Forms versions this might be different (I don't know as I didn't look it up).
You whould do the SQL*Net config like you'd do it on any other oracle client:
except for reports where in the opmn.xml the TNS_ADMIN variable is set for the reports servers; so you'd have to place your config files under $INSTANCE_HOME/config as well.