How to specify EFI System Partition's mount point in ubu installer?

[PGNet Dev]

I'm installing ubuntu-server 16.04 LTS in a Xen Guest/DomU.

I pass pre-formatted LVs to the guest, and boot the ubu installer.

I select 'manual partitioning', and see as expected, the drives I've 
passed through from the host's cfg.

The first drive listed is the expected EFI partition

	Virtual disk 1 (xvda) - 134.2 MB Xen Virtual Block Device
	    1.0 MB        FREE SPACE
	#1 133.2MB  B  K  ESP          ESP

when I select/enter partition #1 to attempt to make changes, there's no 
option to set the mount point for this partion; I see only,

	You are editing partition #1 of Virtual disk 1 (vxda).  This partition 
is formatted with the FAT32 file system.

	Partition settings:

		Name:          ESP
		Use as:        EFI System Partition
		Bootable flag: on

		Resize the partition (currently 133.2 MB)
		Erase data on this partition
		Delete the partition
		Done setting up the partition

I'd like to specify the mount point, as I do in other OSs. 
Specifically, in this case, to

	/boot/efi

( '/boot' is on a separate partition ...)

and, subsequently, have that populated correctly as a mount in /etc/fstab.

How can the EFI partition's mount be specified/set?