ok, sorted it out myself
cp /etc/e-smith/templates-user/.qmail/18filter /etc/e-smith/template-user-custom/18filter
commented out the specific check for the admin user
signal-event email-update
Results in .procmailrc being created and procmail running
then edited .procmailrc to do what I want.
Note: the .procmailrc will still get overwritten on email-update, but I save it as .procmailrc.txt in the user directory, and have a small script to copy it to the .procmailrc every hour. A real kludge,but it works ok. Means an occasional risk of not processing emails for up to an hour.
If anyone has a better way of safely incorporating hand written procmail rules, I'd like to hear it!!