Is it possible?

To grow any kind of useful mushroom / fungi on alders or conifers?  My property is loaded with a mixed stand of alders and ancient cedars with other kinds of conifers mixed in.  I want to cut high and inoculate them with spores, but unsure what I can do since I mostly read about hardwoods.

Please advise.

I'm pretty sure that you could grow regular oyster mushrooms and shiitake on the alder logs. King Stropharia will grow on the chips and sawdust from alder as well. In fact, fresh alder chips and sawdust combined make great mushroom growing block substrate for several different wood-loving species. Ancient cedars (Chamaecyparis spp.), on the other hand, are famous for being resistant to many kinds of fungi. I'd leave the old cedars alone.

Cedars and many of the conifers (pine, spruce etc.) have aromatic compounds that inhibit fungal growth. Some conifers, like Douglas Fir and Hemlock, have fewer of these anti-fungal compounds and might work.

You can inoculate logs and stumps with spores (spored chainsaw oil is available for this task) but for more reliable results you might want to use wood dowel plugs or sawdust spawn, both of which are available commercially. (Another technique is to use rope spawn, but you will probably have to make that yourself.)

Be sure and read Mycelium Running by Paul Stamets for more details and step-by-step instructions on inoculation techniques. It should be available through most library systems.