Writing registry values with multiple '%' signs

Hi Experts
I have to write Registry values like this one:
brc_playout_time=%%%|brc_line=%%%|...

So far I did not found a way to get '%%%' into the registry using the "edit registry" function (SetupBuilder 7.7.3720). I did a lot of experiments:

var -> result -> comment
%% -> % -> this is ok
%%%% -> % -> this is not ok, expected result: %%
%% %% -> % % -> this is ok, but I don't need the space char

Can anyone help me, how get '%%' etc. into the registry?

Regards
Martin