Installment Sale and Schedule C

I have a client that makes a living building and remodeling houses.  He started building a house on land he already owned and one of the subcontractors wanted to purchase it.  The sub contractor did not charge for his labor to lower the contract selling price.  My client then did an installment sale to his sub contractor.  When I prepare the 6252 installment sale and link it to Schedule C (I know the profit should be subject to social security tax) it doesn't flow through to Schedule C.   I did set up an asset entry worksheet in Schedule C and reported the sale and linked it to 6252. No matter what I do it will not flow to Schedule C.   Anyone else had this problem?  Should I not prepare the installment sale and enter income and expenses on Schedule C and then just report the interest income each year?    Of course if I do that all the profit is taxable in the current year.   He is not against paying tax on the total gain this year but it would be better is we could spread it out the number of years on the amortization schedule.  I really want to report it correctly. I certainly don't want it to come back and haunt me.