Tiger is more exacting with permissions on StartupItems scripts. Your script's enclosing folder, as well as the contents need to be set to u=rwx,go=rx (user has read/write/execute permission, group and everyone have only read and execute; by user, I mean root). To apply this to your StartupItems script folder, assuming it's in /System/Library/StartupItems, and it's called "StaticRoutes", let's first change the ownership:
chown -R root:wheel /System/Library/StartupItems/StaticRoutes
(add "sudo " at the beginning if you're not running as root while you type it, or you'll get an "Operation not permitted" error)
This will change the owner of the StaticRoutes folder to root, and the group to wheel (though this doesn't really matter, Apple's StartupItems permissions are set that way). THE -R OPTION APPLIED IT TO ALL ENCLOSED ITEMS (I add this note in all-caps, because -R can be dangerous in the wrong hands, as you can apply the wrong ownership to "/" (the top level of your drive, but just as easily to any number of other special directories) and kill any chance of starting up properly again. The alternative, however is to to a chown for every item separately.
The next thing you want to do is change the permissions so only root has full access to the folder and its contents:
chmod -R u=rwx,go=rx /System/Library/StartupItems/StaticRoutes
Again we're using the useful but dangerous -R option to apply the permissions to the contents as well. "u" means "user", or in our case, root. "g" means "group", which could be set to anything, but we're using wheel because Apple uses wheel. "o" means everyone. Don't add a space between u=rwx and go=rx, or you'll get an error. If you're not logged in as root as you type this, you may also get an "Operation not permitted" error -- add "sudo " to the front of the command. You could also get fancy with the options and do something like "u=rwx,g=u-w,o=g" (which means u=rwx, g=whatever u is, minus write privilege, and o=whatever g is), but that's better saved for another time...
The upshot of all this is that if you change the ownership to root, and the permissions to u=rwx,go=rx for your script folder and its contents, you'll have a fully-functioning script (assuming you remembered to add the line to hostconfig). I've had to change the permissions on all my custom StartupItems scripts, since they were set incorrectly for Tiger.
If you're leery about using Terminal, the excellent and free BatChmod will do the same thing with a graphical interface (see VersionTracker.com for download link).
--
B.Henderson: The script Gary Bidwell posted tests to see whether the line "STATICROUTES=-YES-" (those are hyphens, not underlines) exists in the /private/etc/hostconfig file -- if it's not, or if it says "STATICROUTES=-NO-", then the script won't continue running.
--
ccohen: $1 is the word "stop", "start", or "restart" you should be typing after the script name (ie if you wanted to start the script manually, you'd type "/System/Library/StartupItems/StaticRoutes start" (or drag the file into the Terminal window to add the path and filename, then type "start" at the end -- $1 is the first variable passed to the script (just as $2 would be the second, for a more complex script)). I'm not sure why you're at line 42, because when I copied and pasted the script from the webpage, I got "RunService $1" at line 40...