I have to agree with all of those they say you are trying to make lemonaid with apples, it just ain't gonna work

You have to either convert to their style or maybe meet somewhere in between your two styles.
If the group insists on hack and slash, and that is what they are used to and want, then they need a hack and slash DM. You can either give them that, or move over and let someone else. But, getting mad at them for their likes is not a realistic option, they have just as much right to game their way as you do to game your way. You might be able to get them to gradually change their gaming style, but I think they are probably more interested in the company and laughs, than the RPing side, so don't hold your breath on that one.
I like MonsterForge because it lets me whip out a random encounter in a couple minutes for 3.5, my game of choice. If you use something like that, you can prepare your encounters in minutes instead of hours and just sit back and enjoy the game with everyone else.
Want to spice it up a bit? Talk to the players, tell them you want to make a more exciting experience, if they agree, great. If they don't want change, respect that too and move on to another group. But if they are willing to try something new, when he crashes through the door, have a fully advanced half fiend phasm cast blasphemy on him. No save... hope the rest of the party gets to save him in time, assuming he is even within 10 levels

. Then have the price of a true resurrection be the most twinked out item he has. He will get the message you want him to think before jumping in.
If the party thinks this is way unfair, then you can remind them they wanted a more challenging and exciting dungeon, and if they decide that this isn't what they want, once again, it looks like you won't have much choice other than to find new players. This would really suck, since there are only so many gamers in any given area. You could try to recruit more at your local game store, or even go online and try to make an online game. But when you are recruiting new players, make very sure you explain the amount of combat/action to roleplaying % to them before they join or they will leave just as quickly as they came.
Hope you find happiness and fun in your gaming regardless of how it turns out, gotta remember it is supposed to be fun, not a job, so have fun and relax and enjoy the company if you can.