Hence we had find alternative ways of getting this done.
Thanks to some nice articles by very good people we found a way.
i have posted a link which states how to do this. also i have copied an example here.
but the thing is nobody can guarantee that these will work with all the roll ups that Microsoft are putting out. hence be careful with these.
var fetchStr = "
crmForm.all.new_accountid.lookupbrowse = 1;
crmForm.all.new_accountid.additionalparams = "search=" + fetchStr;