If I understand your original question, it seems that you want to multiply some given complex frequency response sequence and the FFT samples of a time-domain "test" sequence to produce a filtered-signal's spectral samples. Unless I'm missing something, if you have N complex frequency response samples then just multiply those samples by the complex spectral samples of a standard N-point FFT of your time-domain "test" sequence. (No need to worry about linear or log freq axes.) This will yield the complex spectral samples of the "filtered-signal".
If you then want to compute the corresponding time-domain filtered-signal sequence, just compute the inverse FFT of the filtered-signal's spectral samples. Warning: to compute an inverse FFT you must ensure that your filtered-signal's spectral samples cover the full freq range of zero Hz –to- fs Hz and have the appropriate conjugate symmetry.