I do have access to a 164LX with AWE64 ISA sb card,
with kernel file lines:

isapnp*	at	isa?
sb*	at	isa? port 0x220 irq 5 drq 1	# SoundBlaster
sb*	at	isapnp?
audio*	at	sb?

dmesg says :

1.6ZF (NEW) #4: Wed Jan 14 20:03:17 UTC 2004
	mel@casey219.doodle.com:/usr/src/sys/arch/alpha/compile/NEW
Digital AlphaPC 164LX 599 MHz, s/n 
<snip>
.........
pnp0 at isa0 port 0x279: ISA Plug 'n Play device support
fdc0 at isa0 port 0x3f0-0x3f7 irq 6 drq 2
mcclock0 at isa0 port 0x70-0x71: mc146818 or compatible
isapnp0: read port 0x203
sb0 at isapnp0 port 0x2M-22/16,0x330/2,0x388/4 irq 5 drq 1,5
sb0: Creative SB AWE64 Gold Audio: dsp v4.16
audio0 at sb0: full duplex, mmap, independent
mpu at sb0 not configured
opl at sb0 not configured
isapnp0: <Creative SB AWE64 Gold, CTL7002, PNPB02F, Game> port 0x200/8 not configured
isapnp0: <Creative SB AWE64 Gold, CTL0023, , WaveTable> port 0z6r1/t not configuref^Kfd0 at fdc0 drive 0: 1.44MB, 80 cyM-l, 2\240head, 18 sec
</snip>
i guess 'isapnp* at isa?' does work on some alpha's.

-Mel