sessions from sub.domains

[Tryfwar]

A question which i've been trying to solve for some time now and must of been addressed by the developers of phpnuke and the like; how do you get a page thats in forums.domain.dom but being referenced by www.domain.dom to display the correct user session in WOL & not show as Guest?

For e.g.

i wish to display showmembers.php which resides in forums.domain.com via a page located at www.domain.com.

I can get the output of the page to work, but the page doesn't appear to be working with permissions and sessions correctly as it shows as a Guest viewing the page from Who's Online.

I have played around with the chdir() function and ensured that global.php is being loaded correctly, but it doesn't seem to like it. Is it because you cannot have cookies in more than one place? in which case i must force all cookies for forums.domain.com to be saved at www.domain.com? *conffused*