Something

router bgp 65535
 bgp router-id 10.0.0.1
 network 10.0.0.0/22
 network 10.0.0.0/23 route-map noexport
 redistribute ospf route-map noexport
 neighbor 192.168.1.1 remote-as 65534
 neighbor 192.168.1.1 prefix-list validaddr in
 neighbor 192.168.1.1 prefix-list allad out
 neighbor 192.168.2.1 remote-as 65533
 neighbor 192.168.2.1 prefix-list validaddr in
 neighbor 192.168.2.1 prefix-list allad out
 neighbor 192.168.2.1 route-map prepend out
!
ip prefix-list validaddr seq 5 deny 10.0.0.0/8 le 32
ip prefix-list validaddr seq 10 deny 127.0.0.0/8 le 32
ip prefix-list validaddr seq 15 deny 169.254.0.0/16 le 32
ip prefix-list validaddr seq 20 deny 172.16.0.0/12 le 32
ip prefix-list validaddr seq 25 deny 192.0.2.0/24 le 32
ip prefix-list validaddr seq 30 deny 192.168.0.0/16 le 32
ip prefix-list validaddr seq 35 deny 223.0.0.0/8 le 32
ip prefix-list validaddr seq 40 deny 224.0.0.0/8 le 32
ip prefix-list validaddr seq 45 permit any
ip prefix-list allad seq 5 permit 10.0.0.0/22 le 23
ip prefix-list allad seq 20 deny any
!
route-map noexport permit 10
 set community no-export additive
!
route-map prepend permit 10
 set as-path prepend 65535 65535 65535
!