How to set tab to 4 spaces w/out using expandtab in vi (not vim)

I'm normally a vim user and now I'm forced to use vi. Is there a way to set tabs to 4 spaces? I'm not talking about setting tabspace=4, but actually setting a tab to equal 4 individual spaces (thi开发者_开发技巧s is normally done in vim using expandtab).

It may not be pretty, but :%s/\t/ /g, where what's between the second group of slashes is four space characters, should work.