Note: This only works if you freeze your tori for a considerable succession of frames, like 20 or so, or else it isn't noticeable.
Step 1: Open your replay with notepad (you go to your Toribash folder, then to the "replays" folder, right click the desired replay, "Open with", and select notepad)
Step 2: Go to the FRAME line where you want start to completely stop and freeze your Tori (remember that in a 500 matchframes replay, the line "FRAME 100" is what happens on the displayed frame 400 in-game http://imgur.com/eUUTlD5)
Step 3: Delete the POS, QAT, and ANGVEL lines for ALL of the frames where you want the freeze to happen
Step 4: Write the FRAME lines for all of the consecutive frames you want the freeze to last (if you want a freeze from FRAME 400 to FRAME 410, there MUST be a line FRAME 401, a FRAME 402, a FRAME 403, a FRAME 404, FRAME 405, FRAME 406, FRAME 406, FRAME 407, 408, 409, and 410)
Step 5: Replace ALL the LINVEL lines on the frames you want to freeze by this one for tori: LINVEL 0; 0.000000 0.000000 0.000000 0.000000 0.000000 0.000000 0.000000 0.000000 0.000000 0.000000 0.000000 0.000000 0.000000 0.000000 0.000000 0.000000 0.000000 0.000000 0.000000 0.000000 0.000000 0.000000 0.000000 0.000000 0.000000 0.000000 0.000000 0.000000 0.000000 0.000000 0.000000 0.000000 0.000000 0.000000 0.000000 0.000000 0.000000 0.000000 0.000000 0.000000 0.000000 0.000000 0.000000 0.000000 0.000000 0.000000 0.000000 0.000000 0.000000 0.000000 0.000000 0.000000 0.000000 0.000000 0.000000 0.000000 0.000000 0.000000 0.000000 0.000000 0.000000 0.000000 0.000000
Step 6: A successful freeze in notepad should look somewhat like this: http://imgur.com/ne0qzUl