How to enable core dumps

Hello,

I need to debug mathopd process because it segfaults every 2 day. The 
pattern is always the same. Something like "mathopd[24068]: segfault at 
a17b000 ip 005be8ac sp bfd6098c error 4 in libc-2.7.so[54d000+153000]"

I am sure it is not the problem of mathopd itself, but custom patches 
applied to the sources. I can't find the way to enable core dump for 
mathopd. If I run just `./mathopd` and kill it with SIGABRT (on Linux) 
it dumps core. If I run `./mathopd -f /etc/mathopd.cfg` it doesn't. I 
guess it is related to the user_id of running process.

In /etc/mathopd.cfg I have:
User www
StayRoot On

I can't change this because I need to debug real working process. Is 
there any way to enable core dumps without changing my config?

-- 
Dmitry