NAT for syslog connection initiated by pfsense itself

[skywalker]

short Q:
runnning pfsense on nanobsd (alix board).
I want to send pfsense syslog to remote host on a different port than 514.
I thought I can just create a NAT rule to NAT the outgoing syslog packet on LAN interface from pfsense to a different port. But I have no success with that.
Is that possible at all?
thanks!