HASH: Out of overflow pages. Out of luck.

Does anyone have experience hacking the HASH index code to allow more
overflow pages?

I get the following when indexing a table with about 300M entries:

db=# \d table1
       Table "table1"
 Attribute |     Type     | Modifier
-----------+--------------+----------
 field1    | varchar(256) |
 field2    | integer      |
 field3    | float8       |

db=# create index table1_field1 on table1 using hash(field1);
ERROR:  HASH: Out of overflow pages.  Out of luck.

This also happens for field2.

I looked in the source for postgresql-7.0.3 from
src/include/access/hash.h:

 * The reason that the size is restricted to NCACHED (32) is because
 * the bitmaps are 16 bits: upper 5 represent the splitpoint, lower 11
 * indicate the page number within the splitpoint. Since there are
 * only 5 bits to store the splitpoint, there can only be 32 splitpoints.
 * Both spares[] and bitmaps[] use splitpoints as there indices, so there
 * can only be 32 of them.
 */
#define NCACHED            32

Is there a way around this?!  If not: what a horrific limitation.

Thanks!  John