I've never heard of anyone doing that. I'm pretty sure it would require extensive modifications, and in fact I don't think it could be done with an practical level of effort.
More importantly, the Lee 6-cavity mould handles have become the defacto standard. All the semi-custom mould makers build their moulds to take Lee handles (MP, NOE, Accurate). And the Lees can be modified to fit Lyman and RCBS moulds without too much trouble. I recommend switching your mentality to "Can I take the handles off my Lee 2-cavity moulds, throw them away, and make a 6-cavity handle fit instead?".