TACACS+ is supported above revision 4.x
https://www.cisco.com/c/en/us/support/docs/wireless-mobility/wireless-lan-wlan/91631-uwn-tacacs-config.html?referring_site=RE&pos=1&page=https://www.cisco.com/c/en/us/td/docs/wireless/controller/8-2/config-guide/b_cg82/b_cg82_chapter_01010.html
Provides step by step procedure on configuration tacacs + server for unifies wireless communications using cisco wlc, acs and aps