PA-8E in a 7204 as switch

Not really since router would not know where to send a packet. It wouldn't even allow you to put address from the same subnet to more than one physical interface.

You could do several other things:

1) Use IRB - I wouldn't recommend, last time I've used it, it was pretty buggy

2) Use PPPoE with ppp multilink (if possible in your situation)

3) make subnets of your network and assign addresses from subnetworks to individual interfaces (then you'll have some problems but possible to solve)

4) Use Etherchannel if supported.

5) I had one more idea but forgot it while writing 1 to 4 ;-)

HTH,

Why would you do that? If you need a switch, you should use a switch. I suppose BVI is your next best answer, but any and all BVI (IRB,CRB ect) are buggy as far as I'm concerned.