DonÂ't bother, found a workaround:
In Description.ext, itÂ's possible to set a default text:
class RscEdit
{
type = CT_EDIT;
idc = -1;
style = ST_LEFT;
font = FontHTML;
sizeEx = 0.02;
colorText[] = {0, 0, 0, 1};
colorSelection[] = {0.5, 0.5, 0.5, 1};
autocomplete = false;
text = "Default Text";
};