Of late, I found myself enjoying (finally) use of alchemical fire with my rogue in living greyhawk, and (cause I was fighting non-sneak-attackables) contemplating the wonders of 1d6 alch fire + sneak dice that add in as more fire damage. Great way to keep a troll down
I made an alchemist, but given that craft (alchemy) in 3.5 now requires a caster level, I had to choose Bard to keep that kind of feel. (I also wanted decent BAB. I guess a Cleric could do it too, but they eventually get flame strike and other spells that make alch fire worthless, and the bard gets LOADS of skill points.)
For a homegame, it would work fine. He is Human, 10 INT, 4 ranks in craft:alch, and skill focus Cr:Alch so he can craft Acid at 1st level. Also, every +1 in the skill speeds up production time. And yes, I made him purely for a homegame, should another one start locally. (Our 10th level chars are having too much fun in City of the Spider Queen right now.)
My Bard spells would be mostly afterthoughts, though of course I'd have to take staples like Haste. Bards shouldn't Brew Potions because their minimum caster level sucks, so best to stick with Alchemy. Bardsong gives me something to do in any battle if everything is acid- and fire- immune.
The Rogue alchemist would be more fun with the sneak attack, but you'd have to multiclass to a caster level, and lose another BAB. Oh well. At least they can buy as much alch fire as they have GP in Living Greyhawk
Try a Bard w/ Craft: Alchemy. You should be able to have a good amount of fun. Grab archery feats, as pb shot adds +1 to hit and damage to your alch projectiles.
Also try and get the DM to allow the "Gnomish Calculus" from the Arms and Equipment Guide, as it is an oversized sling that lets you throw alch fire w/ a 50' range increment instead of 10'.