By and large you still can do it via GUI. Launch client ==> check "Standard wallet" ==> Click Next ==> check "I have already a seed" == > Click Next == > Click Options == >  check "Bip39 a seed" = > Click OK == > Enter your BIP 39 SEED ==> check "legacy (p2pkh)" (you may also change the last index in derivation path if know what you are doing) ==> Click Next

" and Bob's your uncle!"