I don't think there is a separate bleed for ABS, only for ASR (traction control). I just did my '95 E300D, with ABS (of course) and there is nothing in particular for the ABS. If you have ASR on your W124, there should be a bleed nipple on the ABS pump, and you bleed it the same way as the calipers.

I see you have an E420 - I suppose you do have ASR.

It is described in Stu Ritter's W124 Bentley book.

Have at least 2 liters of new brake fluid on hand for a full flush. You'll love the Motive Power Bleeder. Far better than the ol' Mitey Vac for bleeding!

Rgds,
Chris W.