YES, I've got it.... just thought I should let you now....
and you wouldn't believe how I got it to work......

In the head tag of the left frame page, ie the html containing the flash buttons, add this and all the button will target the same frame:
(this in combination with snOwn's "getURL("/whatever.html", "contentFrame");" on the flash button itself (within Flash))

<BASE TARGET="mainFrame">
(providing the frame to load the content is called 'mainframe' obviously)

See ya!!!!!!!!!!!!!!!!
Happy flashin'
Prisca