Slide guitar master Arlen Roth has a great standard-tuning slide-guitar lesson posted at Gibson.com:

Playing slide guitar in standard tuning – as opposed to an open chord tuning – is very different, and quite difficult because you have to take extra care in damping the strings. When you play slide in an open chord tuning, you always have that chord to go back to. Unfortunately, that’s not the case in standard tuning.

As you’ll see in this lesson, the chord positions are few and far between in standard tuning, but they do exist. Particularly for the G (or A) position, the Em position, and of course, the top two strings which are consistent with what you’re usually doing in E tuning.