HCI 5 will be easy one. Use a spined runic, select Powerful > Grand > Inspired > Slaughter. 4 charges per try so you can get 11 attempts out of each runic. Now, if you wanted MR3 and 5HCI, you would need to burn 2 more charges each attempt and specify from 3 choices which could all end up placing MR on the armor. I would go with Mystic since Arcane and Invigorating both have "Armor Only" mod chances which you do not want here. Note that if you try and up the power with Structural, Fundamental (or both), then you can not select Slaughter.
I just made a studded gorget, with MR3 and HCI 4 just for kicks. The only time I have gotten HCI 5 was when trying for only the HCI. If you can live with HCI 5 and MR2, that would be much easier since you can imbue the MR2, but that is not what you asked.
Good Luck.
-Loren. a.k.a. Armani