Oracle 11g and 10g developer suite harmonisation

Hello,

I have inherited a standalone desktop which had Release 2 (9.2.0.1.0) for Windows (XP) installed on it. I installed 11g on a separate home. All is working well and fine. I know want to install the forms and designer which I understand is Release 10.1.0.4. Please can someone advise what is the best way to proceed? I understand there is an issue with the listner and home ....you cannot have a listening location from oracle 9 listening for database locations higher then 9i when you have 9i and 10g/11g??? And also 11g must be separate from 9i/10g home??? What shall I do have a signle listener on 11g listening down at 9i and 10g database locations or what?

As a rule of thumbs I have at least one listener per instance.

Don't want to cause an outage on multiple instances just because a single listener has to be bounced.