Does anyone know what the disclosure requirements are for second mortgage loans with lender paid pmi?

Can't help much, as I've never dealt with PMI of any kind on 2nd mortgages.

Other than Homeowner's Protection Act, I'm not aware of any regulatory requirement. So, I believe the question is whether a second mortgage is subject to the Homeowner's Protection Act. I think it could be:

(15) Residential mortgage transaction
The term "residential mortgage transaction" means a transaction consummated on or after the date that is 1 year after July 29, 1998, in which a mortgage, deed of trust, purchase money security interest arising under an installment sales contract, or equivalent consensual security interest is created or retained against a single-family dwelling that is the principal residence of the mortgagor to finance the acquisition, initial construction, or refinancing of that dwelling.

Of course, the HPA has neither a regulation nor a commentary, so it's anyone's guess what "refinancing of that dwelling" means.

We provide the notice on our HELOCs and 2nd mortgages as part of the committment letter, however the template does not quite fit. HPA98 outlines (mandates) a comparison of loans with borrower paid PMI versus with lender paid PMI. We could not find where any PMI companies offer borrower paid PMI for 2nd mortgages, so we made a statement to that effect in lieu of the comparison matrix. There are vendors that have the disclosure in their document inventory, but much of it is completed by the lender.

Based on the definition, it seems that we only need to be concerned with giving the disclosures if the loan is secured by a primary residence.

We have developed a disclosure to give to the borrower at closing - for lender paid PMI. It is the second requirement - "not later than 30 days after the termination date that would apply in the case of borrower paid MI, the servicer shall provide to the mortgagor a written notice indicating that the mortgagor may wish to review financing options that could eliminate the requirement for private MI in connection with the residential mortgage transaction", that I am struggling with now. If we do not have the first mortgage, I don't see how we can comply with that section of the Act. Perhaps we could request the applicant to provide an amortization schedule on the first mortgage (which is at a different institution) and determine when the LTV would reach 78% using the original amortization schedules.
Would this be in compliance?

HPA98 only applies to single family primary residences. The whole section addressing LPPMI was written for 1st lien mortgages, not seconds. It's virtually impossible to comply based on the slant. Too bad no regulation was written - perhaps that would have been thought through more thoroughly!