$reg->param, $req->body - is there a way to set form data?

Hi all,

I have in my code what used to work on 1.0. I have this variable, $form, 
which is a reference for $req->param. I had cases in the code where 
something is submitted in a form that is incorrect, and I want to change 
the op of the form by setting $form->{op} (the code has a hash reference 
to different subroutines that are keyed by op's value). Now when I do 
this, I get this error:

Can't locate object method "STORE" via package 
"APR::Request::Param::Table" at 
/var/www/perl-lib/WebLib/Application/UserReg.pm line 360.\n, referer: 
http://www.patg.net/userreg

Reading the docs, it looks like you can't _set_ a value this way any 
more. Or can you? Is there a way? It's pretty important that I can do 
this. Otherwise, more re-writing.

Thanks in advance for info on this.

--Patrick