Hi,
Not with communities, but i can suggest in another way. For eg assuming, your complete network block is "192.168.32.0/19". Then, i'll segment this into "192.168.32.0/21", "192.168.40.0/21", "192.168.48.0/21" and "192.168.56.0/21".
My Adv to ISP's like this...
To ISP-1
192.168.32.0/19, 192.168.32.0/21, 192.168.40.0/21
To ISP-2
192.168.32.0/19, 192.168.40.0/21(with AS-path prepend), 192.168.48.0/21
To ISP-3
192.168.32.0/19, 192.168.48.0/21(with AS-path prepend), 192.168.56.0/21
Like this, according to your customers,their application analysis and your uplink capacities, you can do variable supernettting and advertisements. So, that if one ISP-1 is down, that traffic can divert through other ISP-2 as outside world sees the next best longest prefix from ISP-2.
Note : Don't forget to advertise your aggregate route to all providers along with your subnets.
We are using the same and working fine without any manual intervention during outages of uplink/s.
Regards...
Ashok.
With best regards...
Ashok