Web Proxy + Hotspot

Hello All

I want send all proxy users to hotspot login page for authentication with radius server. before all, I need to ensure whether hotspot can be set on global (outside) interface ? does anybody have done with this solution before ?

I need to do this because I can not authenticate web proxy users, but if I send them to hotspot I will be able to restricting web proxy access and authenticating users.

I will be grateful if anybody could help me to setup.

Best Regards
AliYashar