Shared memory error using initdb on Solaris 8

Hello,
I'm trying to install PostgreSQL 7.4.2 on a brand new SunFire 120 with
2GB of RAM but when I run initdb -D /usr/local/pgsql/data I get the
following error:

creating directory /usr/local/pgsql/data... ok
creating directory /usr/local/pgsql/data/base... ok
creating directory /usr/local/pgsql/data/global... ok
creating directory /usr/local/pgsql/data/pg_xlog... ok
creating directory /usr/local/pgsql/data/pg_clog... ok
selecting default max_connections... 10
selecting default shared_buffers... 50
creating configuration files... ok
creating template1 database in /usr/local/pgsql/data/base/1... FATAL: could
not create shared memory segment: Invalid argument
DETAIL: Failed system call was shmget(key=1, size=1081344, 03600).
HINT: This error usually means that PostgreSQL's request for a shared
memory segment exceeded your kernel's SHMMAX parameter. You can either
reduce the request size or reconfigure the kernel with larger SHMMAX. To
reduce the request size (currently 1081344 bytes), reduce PostgreSQL's
shared_buffers parameter (currently 50) and/or its max_connections parameter
(currently 10).
If the request size is already small, it's possible that it is less
than your kernel's SHMMIN parameter, in which case raising the request size
or reconfiguring SHMMIN is called for.
The PostgreSQL documentation contains more information about shared
memory configuration.

initdb: failed
initdb: removing data directory "/usr/local/pgsql/data"

When I run ulimit -a I get

time(seconds) unlimited
file(blocks) unlimited
data(kbytes) unlimited
stack(kbytes) 8192
coredump(blocks) 0
nofiles(descriptors) 256
vmemory(kbytes) unlimited

There does not seem to be an option in initdb to reduce the shared buffers
size. Plus, with 2GB of RAM I don't know that I'd want to go below the
"lowest common denominator" that Postgres defaults to.

Kevin