Cross cert interoperability

I have two servers 0ne is V5.07 upgraded from 4.6.7 but for operational and database reasons we did not upgrade the PNAB. I also have a V6.01 web server in a different domain. I need to cross certify or somehow have these two servers replicating with each other. Due to the new global id, the V5 server will not accept the V6 cross cert.

In the Dom V6 admin database it states under security:

User and Server IDs contain a flag bit that indicates that the ID is North American. Global editions of Lotus Notes/Domino 5.0.3 and later ignore this flag. However, earlier international editions of Lotus Notes/Domino (Notes/Domino 5.0.2 and earlier) recognize this flag and refuse an ID marked North American. If you require an ID that works with earlier international editions of Lotus Notes/Domino, create an ID with an earlier international edition of Lotus Notes. For earlier North American editions of Lotus Notes, use a North American ID. You can use an international ID; however, those IDs have a weaker cryptography than the North American IDs.

How can I use an older Cert.id in Dom 6?

Does anyone know anyway around these difficulties?

Many thanks

Don.