Here is the datasheet for 4900M :
you may search for VRF and it looks like Enterprise Services image supports VRF Lite
For 4500-X :
• Cisco IOS XE Software IP Base:
Includes all Layer 2 features and some basic Layer 3 features.
• Cisco IOS XE Software Enterprise Services:
Upgradable with a Software Activation License (SAL); supports full Layer 3 protocols and advanced features such as complete routing scalability, Border Gateway Protocol (BGP), Virtual Routing and Forwarding, Policy-Based Routing, and so on.
All 4K support only VRF-Lite.
The "smallest" Cisco Catalyst multi-layer switch that supports full VRF is the 6500E Sup7E or ME3800X.
6500E Sup2T also supports full VRF.