I use a fire-arrow rogue for my skelliemancer, and in act one, Hell, I'm tempted to replace her.
The Immolation Arrow (Napalm Hose) prevents me from seeing anything in her area of effect. And the fire area damage is rather small compared to hell monster life. I equipped the Rogue to do elemental damage since my skellies take out anything that isn't physical-immune. However, even with a weapon that has 200-300 fire and 200-300 cold damage plus 3 Zods plus her immolation Arrow effect, she is a very slow killer.
Her sanctuary aura is helpful, but the skellies would be more helped by Defiance or Might. I hoped the Aura would do significant damage but things aren't that way. Even with a ring giving +15 to sanctuary and +5 all skills in other items, her aura damage is very small.
Using a Rogue to help a Hammerdin... I'd think an act5 barb would be the best blocker. I'd give him FRW (Mr Sulu, go to warp factor 4) and crushing blow equipment so only Immune to Physical/Immune to Magic monsters are a bother, for that the pally needs a second attack method (Vengeance/Fanaticism since in Hell the barb supplies Conviction)