Polices

I'm assuming you're talking about importing System Policy that you've already created and stored under C:\winnt\system32\repl\import\scripts.
On PDC, first you'll need to copy the saved policy from the directory above and save it to the C:\winnt\system32\repl\export\scripts directory, then
go to admin tools, server manager and click replication,then select "Export directories" on the left hand side, type "c:\\winnt\system32\repl\export\scripts" in the "from Path" box. Underneath click "Add" and select your BDC's name.
In the "Logon Script Path" type in "C:\winnt\system32\repl\import\scripts". On the right hand side click "Do not Import" and click "OK" to close the window. Now go to the BDC, admin tools, open Server Manager, on the lefthand side, click "Do not Export". On the right hand side, click "Import Directories", type "C:\winnt\system32\repl\import\scripts", underneath click "Add" then select your BDC's name. In the Logon Script Path box type in "c:\\winnt\system32\repl\export\scripts" and click "OK" to close. The Importing of the files will take a while to start. If you want to make it effective right away you can use a floppy and copy the policy file from PDC and save it to the C:\winnt\system32\repl\import\scripts on the BDC.
Hope this helps.