Did you mean virtual routers? I've never heard of logical routers although I've configured juniper netscreens numerous times.
Virtual routers are in-built into Juniper Netscreen's router software architecture and are extremely easy to configure. I don't think extra software or hardware is needed.
What do you mean by 'PIC'?

From: ibtisam jamal <ibty.jamal@gmail.com>
To: Skunkworks forum <skunkworks@lists.my.co.ke>
Sent: Friday, May 8, 2009 10:12:46 AM
Subject: [Skunkworks] juniper logical routers

Hi all,

Has anyone configured logical routers on a physical router specifically for juniper.

i have read that the requirements for a separate routing engine and separate interfaces on PIC.

I need advice from someone whose done this ...need to know the pros n cons.

regards,