FIFO Consumption to calculate Sec.price gain

Hi,

My customer used the product type Shareholdings, as follow:

1. Tr.Type                  Date                                       Price                      Units                                      Total      

BUY                       01.10.2015                          1.052681              239,923,502.5                     239,923,502.50

BUY                       02.10.2015                          1.053644              474,543,583.98                  500,000,000.00

BUY                       05.10.2015                          1.056930              946,136,451.80                  1,000,000,000.00

SELL                     06.10.2015                          1.057974              1,417,804,218.25               1,500,000,000.00

I need to use FIFO Valuation as follow:

To get the following Security Price Gain in tx. TPM12

1. Tr.Type  Date                        Price                       Units                                      Total                      Sec.Price Gain

SELL       06.10.2015             1.057974                 239,923,502.5        239,923,502.50                       1,269,915.10

SELL       06.10.2015             1.057974                 474,543,583.98      500,000,000.00                      2,054,773.72

SELL       06.10.2015             1.057974                 703,337,131.77      744,112,398.65                      40,775,266.88

Total Gain:            44,099,955.69

I customized in:Treasury and Risk Management-> Transaction Manager-> General Settings ->Accounting ->Settings for Position Management->Assign Consumption Sequence Procedure

But the system use Avg. Cost to calculate the price gain, but that is not useful for me.

How I can calculate FIFO to get the total gain?

Regards,

Adriana Rivera