HI Ilia,
Oks, if you haven`t done this, please dont try yourself, not in production system.
If this is indeed allowed your organization and you have the approvals, i`d suggest to get a developer to do this for you, they all know this trick.. you need to SE16 hack that table entry in /sapsll/cuhdsta table for your cusdec and change it from 4B to 1A... it works..
Please only do this once you and your developer know this is allowed and authorized according to your IT policies, and maybe try it with them in development system first !
Regards,
Branio