It's a little tricky to define a menu on the fly in CCP4 Tcl. The trouble is mainly with where to put the quotation marks. I adapted this from dhm_tool.tcl in CCP4i:

                                                                          
    puts "test=($test)"
                                                                                                                                                               
    for { set i 0 } { $i <= $test } { incr i } {
         lappend menulist "$i"
         lappend fileselect(ALIASLIST) $i
    }
                                                                                                                                                               
    incr test
                                                                                                                                                               
    DefineMenu _input_columns $menulist $fileselect(ALIASLIST)

For truly dynamic menus, try varmenus.