So you are looking for client-to-site/remote access VPN connection using MX. No you can't do it, it supports site-to-site VPN only.
You don't need UserID or Username for a site-to-site VPN scenario. Preshared key with encryption methods in phases should suffice.
You can ask your VPN provider to provide required site-to-site VPN parameters, if they allow.
I dont see any standard firewall also supports it. Only option left is using DD-WRT, Tomatoe firmware, etc. Cisco ISR can be used as well.