You can use the "capability vrf-lite" knob to disable the down bit check on the PE router. Care must be taken not to introduce a routing loop while using this knob. For more information about that knob, refer to the following URL:
http://www.cisco.com/univercd/cc/td/doc/product/software/ios123/123cgcr/iprrp_r/ip2_c1g.htm#wp1036522
Hope this helps,
Harold Ritter
Sr Technical Leader
CCIE 4168 (R&S, SP)
harold@cisco.com
México móvil: +52 1 55 8312 4915
Cisco México
Paseo de la Reforma 222
Piso 19
Cuauhtémoc, Juárez
Ciudad de México, 06600
México