Nested CI installation doesn't work

[eluser]nofearinc[/eluser]
Here there are couple of guides that might be of any help - there is light in the tunnel, metaphorically.

Setting multiple sites - useful, although it requests Apache reconfiguration (not applicable on shared hosting)
Subdomain thread - switch HTTP_HOST for multiple subdomains
Routes hacks

and 2 more questionable:

Change the uri_protocol?
htaccess tips - I still think we could workaround with overloading this htaccess.