Adding parameters on an internal_redirect()

[MGUCKEYSON]

What I'd like to do with a particular type of error is redirect with all the
parameters passed to the error-inducing script plus one tacked on for good
measure. 

So if /blah/foo.pl?bar=1 was the script that generates the error, something
like 
$r->internal_redirect( /error/error.pl?type=4 ) would hopefully pass
error.pl both the 'bar' and 'type' params. As it stands now, I can get the
'bar' param, but have had no luck getting the 'type' param added on.

Thanks...
mark