Alvaro,
my package needs xowiki but it loads the procs before loading xowiki
Make sure that "::xo::db::require package *" is definitely called before your first xowiki-dependency (*-procs.tcl that contains a reference to xowiki infrastructure). So, in doubt, place it at the top of your first *-procs.tcl (in alphanumerical ordering) ...
are you sure that there is no other sign of error, possibly entirely unrelated to xotcl-core/xowiki?
//s