bind F11 vstr _ssScr
bind F12 vstr _ssClr
set _ssScr "math _ss_Counter ++; vstr _ss_scr; echo Screenshot"
set _ssClr "math _ss_Counter ++; vstr _ss_hideUI; delay 5 vstr _ss_clr; delay 10 vstr _ss_showUI; delay 10 echo Clear Screenshot"
set _ss_hideUI "set _tmp_drawgun \$$cg_drawgun\;cg_drawgun 0;cg_draw2d 0"
set _ss_showUI "set cg_drawgun \$$_tmp_drawgun\; cg_draw2d 1"
set _ss_scr "screenshotjpeg \$$fs_game\-\$$mapname\-\$$_ss_Counter\-\$$r_width\x\$$r_height\"
set _ss_clr "screenshotjpeg \$$fs_game\-\$$mapname\-\$$_ss_Counter\-\$$r_width\x\$$r_height\-clear"
Ofc requires /math and cvar substitution. Sadly there's no date/time variable nor a way to guarantee not overwriting screenshots if autogen (and _ss_Counter value) is lost.
EDIT: Apparently this needs "/seta _ss_Counter 0" for trem to start storing that value...