ENTRY TAX in MM -need deductible condition

hi,

We need to map Entry Tax in Orissa which a Deductible tax based upon PO BAse valueExciseVATFreightinsurance.

We tried by creating a deductible condition type in TAXINN same of JVRD for entry tax. But the base for it BASBExciseVAT. We couldnt include Freight& insurance in total base value for Entry Tax.

now the question is

1.how to get new base value for Entry tax in TAXINN which include freight & Insurance from MM Schema??

2. Is there any posibility of creating a "Deductible tax condition type" in MM schema??

regards

sandeep