Enabling MPLS on IOS routers is quite forward. Assuming here LDP is the preferred protocol. On directly connected hosts this should be enough to enable MPLS:

conf t
!
mpls ip
mpls label protocol ldp
!
interface Gi0/0
 ip 192.0.2.10 255.255.255.0
 mpls ip
!
end

On not directly connected hosts following configuration is needed, if they should establish a neighborship.

conf t
!
mpls ldp discovery targeted-hello accept
!
exit

Verifying mpls ldp neighbourship

sh mpls ldp discovery

The output will reveal something like this:

This is all one need to know about enabling MPLS on IOS routers. Funny fact is MPLS is enabled per interface, and globally for functionality.