In file dll

# wm.tcl hook command is defined in wm.dll
hook

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# gen.tcl
set so [open so.tcl w]
set pream {
    proc load_dll {} {
	puts "loading dll"
	set so [open [info script] r]
	read $so ; 
	fconfigure $so -translation binary 
	read $so 1 ; # drop ^Z
	set dll_start [tell $so]
	puts $dll_start
	chan seek $so 0 end
	set dll_end [tell $so]
	puts $dll_end
	
	chan seek $so $dll_start
	set dll [read $so [expr {$dll_end - $dll_start}]]
	
	set tdll [open "test.dll" wb] 
	puts -nonewline $tdll $dll
	close $tdll
	load "test.dll" Wm
    }
    load_dll
}
puts $so $pream
puts -nonewline $so [read [open wm.tcl r]]
fconfigure $so -translation binary
puts -nonewline $so \x1A
puts -nonewline $so [read [open wm.dll rb]]
close $so

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generate file with tclsh gen.tcl
now start tclsh so.tcl and the dll will get loaded