Notes:
I've created my own lab to test out the different types of Layer 2 protocols I can transport over MPLS.
There are, at a basic level, 2 parts to enabling AToM. First, create a pseudowire-class and second, create the VC via an xconnect statement under the CE facing interface on the PE.
Of course, the prerequisite for this to work is that MPLS is enabled throughout the core network.
Also, note that to make life easier use 'mpls ldp router-id loop 0 force'. You have to designate the other PE as peer in xconnect which will be the ldp router id.
Layer 2 protocols that can be transported are EoMPLS, FRoMPLS, PPPoMPLS, HDLCoMPLS, and ATMoMPLS (can't emulate in dynamips, as the PA-A1 doesn't support it).
Config:
R3 - PE
mpls ldp router-id Loopback0 force
mpls label protocol ldp
pseudowire-class EOMPLS
 encapsulation mpls
!
interface Loopback0
 ip address 3.3.3.3 255.255.255.255
 no clns route-cache
!
interface FastEthernet1/0
 ip address 150.1.35.3 255.255.255.0
 duplex auto
 speed auto
 mpls ip
 no clns route-cache
!
interface FastEthernet1/1.100
 description EoMPLS
 encapsulation dot1Q 100
 no cdp enable
 xconnect 4.4.4.4 100 pw-class EOMPLS
!
interface Serial2/0
 description HDLCoMPLS
 no ip address
 serial restart-delay 0
 no cdp enable
 no clns route-cache
 xconnect 4.4.4.4 67 pw-class EOMPLS
!
interface Serial2/1
 description FRoMPLS
 no ip address
 serial restart-delay 0
 no cdp enable
 no clns route-cache
 xconnect 4.4.4.4 607 pw-class EOMPLS
!         
interface FastEthernet3/0
 ip address 150.1.34.3 255.255.255.0
 shutdown
 duplex auto
 speed auto
 mpls ip
 no clns route-cache
!
CE config
The CE's are generally configured like back to back CE to CE connections with nothing but a pseudo wire connecting the two. * Remember for FRoMPLS though, you'll want once side to act as Frame switch and that interface to be DCE.