The 4900 WIT can be reset with a model/tank specific resetter - google 'Epson 4900 Waste Ink Tank resetter' - I paid $50 for mine, around the cost of a new tank.
Once you have a resetter, take the full tank apart - I use a razor knife to cut through the foil cover - pull out the cotton batting and replace it with the material of your choice - paper towels, diapers, sanitary napkins - there are lots of materials suggested in various forums. These all work fine, but I do the following:
Wash out the Epson-supplied batting in running water (wear gloves!) or soak in a large bucket/sink overnight then rinse well. Dry them on a radiator or an oven or just leave them out if your humidity is low enough (I had a couple get mildewed so a quick dry is recommended). You can't get all the ink out, so don't spend your life at it...
Repack the tank - remember the order the pads were loaded as some have slots for the waste ink discharge tube and others have square holes in the middle (why?).
Use duct tape to cover the tank - it doesn't have to be perfectly covered but don't leave loose edges to hang up in the tank slot.
If you haven't done it already, reset the chip.
Reinstall the tank (some people insert a new, unused tank first then put in the recycled tank - I don't find this necessary on my 4900s but the tank indicator shows 75% capacity with the recycled tank only)
Start printing again.
I find the cleaned batting doesn't get as messy as paper towel and has about 50-75% of the capacity of a new tank.
One of these days I will weigh a new but full tank and compare it with a new empty tank. That will give me a more accurate gauge of how much ink I'm getting out of the batting and how much ink my recycled tanks are holding when they are 'full.'
I have also tried a single layer of paper towel just to see what kind of accumulation of ink I get. Don't do this w/o covering the tank - the splash will get up in the works and make a mess or worse. Emptying the tank setup like this is a little messy as the liquid ink will slosh around when you pull the tank, but you can pour out the waste ink, reset the chip and get back to printing more quickly than doing the whole batting cleaning cycle.
Note that I mostly use the Cone black ink sets so I'm not dealing with colored Epson ink that much.