I'm not sure exactly what your wanting, but here are a couple of options.
You could:
If you want to just change the outline of the compass you could just set the frame colors.
Lua Code:
ZO_CompassFrameCenter:SetColor(0, 1, 1, 1)
ZO_CompassFrameLeft:SetColor(0, 1, 1, 1)
ZO_CompassFrameRight:SetColor(0, 1, 1, 1)
If you really want it to look exactly like when your in a quest area. I looked, but didn't see any way to use the highlight thats already built in. They are created for the quest pins from a pool & appear to be released when no longer in use. So I think you'de have to make your own, these are the textures for it though. You could just create 3 texture controls (one for the center, left, & right endcaps) and overlay them over the compass:
Lua Code:
"EsoUI/Art/Compass/area2frameAnim_centers.dds"
"EsoUI/Art/Compass/areapin2frame_ends.dds"
"EsoUI/Art/Compass/areapin2frame_ends.dds"