Solution:
TAG memory is nothing more than flash memory cells available for the user's functions. Lattice Technical note TN1213 gives more information on how to access to TAG memory.
ispVM System allows LatticeXP2 TAG memory to be read, erased, and programmed via JTAG, separately from other configuration cells, without affecting those cells. This can be done in Flash Programming Mode and Flash Background Mode. As ispVM System is used to generate ispVME files which are used by embedded processors using Lattice ispVME, the same flow followed in ispVM is sufficient to carry out operations on TAG memory of XP2.