You can ask for the current user-defined ACM by specifying user, or ask a new ACM to be loaded from a file into the user slot, by specifying a filename.
You will note that, although each VT has its own slot settings, there is only one user-defined ACM for all the VTs. That is, whereas you can have tty1 using G0=cp437 and G1=vt100, at the same time as tty2 using G0=iso01 and G1=iso02 (user-defined), you cannot have at the same time tty1 using iso02 and tty2 using iso03. This is a limitation of the linux kernel.
Note that you can emulate such a setting using the filterm(1) utility, with your console in UTF8-mode, by telling filterm to translate screen output on-the-fly to UTF8.
You'll find filterm(1) in the konwert(1) package, by Marcin Kowalczyk, which is available from http://qrczak.home.ml.org/.
charset cannot determine which of the 2 slots is in use at a given time, so you have to tell him which one you want, even if you don't want to change to the other one. This is a limitation of the console driver.
consolechars(8), unicode_start(1), filterm(1).