explorer command line switches with /separate

Just discovered the useful /separate option for explorer.exe which can be
combined with runas to get an explorer window with a different user's
privileges. But it doesn't seem to work if I try to combine /separate with
oher explorer switches, such as /e or specifying a directory to open in. Is
there a special syntax for this or does /separate preclude the use of other
switches?

Grateful for advice.