Thanks for the replies seems i made a balls up above
Basically what i should have said was this
I need a way to redirect
subdomain.example.com to example.com/psp - Thats for the Index page only
for the rest of the subdomain
subdomain.example.com to example.com - Thats for all the content pages and Not the Index page.
Reason for this is so that i can use the new index page to point to the old news/content and not see it lost in google.