The rem-jet backing is best removed after the stop bath and before the blix. The carbon particles are very fine and would be hard to filter out from the blix. Under subdued light, first check to see if the rem-jet coating will come off easily. If not then soak the film for a couple of minutes in a 2% solution of sodium metaborate (Kodak Balanced Alkali). Remove the film from the reel and hang it up. Very gently wipe the base side vertically with a moistened photo grade sponge. Rinse the sponge and repeat if necessary. Be careful not to get any carbon particles on the emulsion side. Return the film to the reel and contnue the process.
Even with the recommended filter the color balance will be off since the C-41 developer is very different from the recommended ECN-2 developer. It will also be a bit off because this film is intended to be printed on color positive stock. The color balance of the positive film is not the same as for color paper.
I have not processed this particular film but others can give good results if the ECN-2 developer is used. Substitute formulas for home processing can be found on the web.