unite-tselect is a unite.vim source plugin
for selecting tags, which provides a similar functionality as :tselect command.
To search tags for <keyword>, execute
:Unite tselect:<keyword>
If you want to remap g<C-]> and g], copy the following lines into your vimrc.
nnoremap g<C-]> :<C-u>Unite -immediately tselect:<C-r>=expand('<cword>')<CR><CR>
nnoremap g] :<C-u>Unite tselect:<C-r>=expand('<cword>')<CR><CR>