Instinctive, isn't yet adopted by AGB, but is used in some tournaments as it is a WA category, and may be adopted by AGB in the future.
My understanding is that adding a weight would not be permitted in the current rules, but I don't think that there is anything in the rules to say that you can't have a bushing fitted for the weight.
The button isn't allowed for AGB Trad or for WA Instinctive, but I don't know of any rules preventing the bushing being fitted.
(AGB Traditional = any riser that fits through the barebow ring, weights attached to the riser directly and no sights with wooden arrows, no string walking or face walking
WA Instinctive = laminated riser containing wood or all wood, no weights unless they are fitted inside the riser when the bow is made, no button, with any arrows you want. No string walking or face walking
At least that's what I understand the rules to be, although I've heard that there may be some changes in the future)