Linux kerberos authentication against multiple subdomains?

[Nils Olav Brandstorp Bekken]

I'm trying to set up a linux (RH 9) email server with imap and 
authentication against multiple subdomains running w2k.

 domain.com (no users logging on here)
 sub1.domain.com (department # 1)
 sub2.domain.com (department # 2)
 ...
 sub5.domain.com  (department # 5)

domain.com trusts each sub domain and each
subdomain trusts the parent domain.

installed packages:
rpm -qa|grep krb

krbafs-1.1.1-9
krb5-workstation-1.2.7-14
krbafs-devel-1.1.1-9
krb5-libs-1.2.7-14
krb5-devel-1.2.7-14
pam_krb5-1.60-1

I've got it to work with one realm in krb5.conf, when I'm putting 
default_realm = sub1.domain.com in libdefaults and defining kdc and 
admin_server in the realm setting. But I got trouble making it work with 
two or more subdomains (been reading faq's, man pages, newsgroups and books 
for the last 2 weeks now) I've been looking at the capath setting, without 
luck. Anyone done this before?

Any help would be appreciated

Thanks in advance

Nils O. Bekken