You can create composite fonts using any one Roman font and the Simplified Chinese Song-Medium-H font. For example, the following PostScript code defines a composite font, Times-Italic+Song-Medium, which uses Times-Italic for ASCII characters and Song-Medium horizontal font for Simplified Chinese characters:
/Times-Italic+Song-Medium 13 dict begin /FontName 1 index def /FMapType 4 def /Encoding [ 0 1 ] def /WMode 0 def /FontType 0 def /FontMatrix [1.0 0.0 0.0 1.0 0.0 0.0] def /FDepVector [ /Times-Italic findfont /Song-Medium-H findfont ] def currentdict end definefont pop