Help advertising a default route with prepends to a BGP neighbor

Any way I can advertise a default route to a specific neighbor with prepends?

I have a private wireless carrier that we have multiple wireless devices on and we peer with them in 2 locations on Cisco ASRs. I have import and export route-maps with a default-originate setup in BGP. When I test this in my lab the export route-map that has the AS prepends and ip prefix-list permit for 0.0.0.0 doesn't seem to be sending the prepends across. It appears the default-originate is it's own special thing and wont add the prepends even if there is a route-map setup to do it.