OK, first thing...
I can't remember about 'turbo mode' but I know that dynamic mode on PC Task 4.0 or greater uses up 4x normal RAM, so that'd be fine as long as you only use 1MB for your PC. Try it and see...

Secondly, MS-DOS 6.00 and above come on HD floppies as standard. MS-DOS 5.00 comes on DD disks. You can put >=6.00 onto 720KB disks but it's hassle. What you should do is create a hardfile or partition and mount it from AmigaDOS. Then copy each file from the DOS disks into an installation directory, and run Setup from there. Of course that won't help you boot up in the first place - you'll need a method of booting up to get that far. You could try looking at FreeDOS and suchlike - that works on 8088 machines so should be ok on 3.5" disks to boot off, from where you can install 6.22 if you really need it.
Now... on to Alone in the Dark.
After spending all morning getting my 386 working (the dual port RAM was misbehaving - I've been using it as a guinea pig while trying to get my 486SLC-based A2386 working), I can say:
PC-Task interpretive runs Alone in the Dark quite impressively, but not really what I'd call fast. It may do at a pinch but you really ought to be looking at a hardware solution. A 66MHz '060 would help of course, mine is 'only' 50. It's playable when just moving around but when things start happening it's less good.
PC-Task dynamic is a lot
slower than interpretive.
A2386SX (25MHz, 5MB RAM, Trident SVGA card) works acceptably but it's a bit stodgy. I wouldn't recommend it really.
GoldenGate 486SLC@25 (16MB 80nS RAM, Thunderbolt ISA CL-based 1MB SVGA, 8-bit Soundblaster II) works perfectly. Much more playable even with the soundblaster.
Overall, I was quite impressed by PC-Task, and the 2386 wasn't much faster that it... but the GG wins hands down. It's surprising how much of a difference the different chip makes!
So, my recommendation: nothing less than a GG486 or a 486-based 2386 (probably - can't get mine to work!). Of course if you stick an IBM Blue Lightning SLC75 onto that 2386....
And no, they're not for sale.
