Hi Ian
Any system for which you can get or make a 4MT adaptor is the quick answer. You can buy ready made 4MT holders for ER collets, and you can use Morse taper collets, if necessary in conjunction with adaptor sleeves. Theres a fair amount of room in 4MT so you should have a good choice even if you make your own adaptor. A number of collet systems have adaptors to fit the nose of the mandrel, rather than the bore so have a look for those as well.
Keith