Not an answer, but close enough for my purposes.
Now I can scroll in xterm by using the Meta (Alt_L) modifier in combination with level3 shifted Prior/Next keys in place of physical 'i' and 'm'.
XTerm*vt100.translations: #override \n\
Meta <KeyPress> Return:fullscreen(toggle) \n\
Shift <KeyPress> Prior:insert() \n\
Shift <KeyPress> Next:insert() \n\
Meta <KeyPress> Prior:scroll-back(1,halfpage) \n\
Meta <KeyPress> Next:scroll-forw(1,halfpage)
For completeness sake this is my modified keymap in case anybody is interested:
hidden partial modifier_keys
xkb_symbols "swapescape" {
key <TAB> { [ Escape ] };
key <ESC> { [ Tab ] };
};
partial alphanumeric_keys
xkb_symbols "ee" {
include "us"
name[Group1] = "English (US keyboard with custom overlay on level3)";
// hjkl
key <AC06> { [ h, H, Left ] };
key <AC07> { [ j, J, Down ] };
key <AC08> { [ k, K, Up ] };
key <AC09> { [ l, L, Right ] };
key <AD08> { [ i, I, Prior ] };
key <AB07> { [ m, M, Next ] };
include "eurosign(e)"
};
Still, I'd like to know if it's possible to make it work without (Meta) modifier.