[CMake] keep semicolons alive

[Maik Beckmann]

Hello

I want to fetch a environment variable which contains semicolon by intention, 
modify it a little and use it with a custom command:

#TEXINPUTS_latex is ":;${workspace_loc}/texmf/texmf/tex//"
SET(TEXINPUTS "$ENV{TEXINPUTS_latex};${PROJECT_SOURCE_DIR}") 
#TEXINPUTS should be ":;${workspace_loc}/texmf/texmf/tex//;/path/to/project"

ADD_CUSTOM_COMMAND(
    OUTPUT       ${PROJECT_BINARY_DIR}/${LATEX_target}.ps
    COMMAND	TEXINPUTS="${TEXINPUTS}" 
                       ${DVIPS_CONVERTER}   
                       ${DVI_FILE_WE}.dvi   -o${PS_FILE_WE}.ps
   DEPENDS    ${DVI_FILE_WE}.dvi
   COMMENT	"dvi -> ps for PDF_${LATEX_target}" )

The problem is that the semicolons are replaced by space " ".

How can I achieve what I want?

Thanks in advance, 
Maik