tsearch2 Upgrade to 8.3 tsearch2.so errors

Hi

I am currently upgrading from 8.1 to 8.3 and am getting errors when
restoring the dump from 8.1 into 8.3. Like below:

ERROR: could not find function "gtsvector_in" in file
"/usr/lib/postgresql/8.3/lib/tsearch2.so"
ERROR: function public.gtsvector_in(cstring) does not exist
ERROR: could not find function "gtsvector_out" in file
"/usr/lib/postgresql/8.3/lib/tsearch2.so"
ERROR: function public.gtsvector_out(gtsvector) does not exist
ERROR: function gtsvector_in(cstring) does not exist

I have read this is due to the tsearch2 functions being moved into the core
section of postgres and I'll need to do some editing after the dump to
change where the functions get referenced.

My question is: ( As I am no dba)
How do I change a create function statement like below so that it will load
correctly in 8.3 and not lose the functionality.

CREATE FUNCTION gtsvector_in(cstring) RETURNS gtsvector
AS '$libdir/tsearch2', 'gtsvector_in'
LANGUAGE c STRICT;

Thanks in advance

Darragh