In theory there are a few financial ways for such deals, the problem is if Pakistan can ,with either one of them,sustainably fund these ''ties'' the Turk mod listed.
For example, how long can Turkey keep funding the sales to Pakistan with credits for those ''ties'' the Turk mod listed. Is Turkey financially strong enough for such sales methods to every country or all products?
Apperantly, the Turk mod is a dream seller. However, the question still waits for a pragmatic answer from both Turkey and the buyer side.
There are a few issues.
1. Generally (not specific to Pakistan), Turkey will need to build a credit financing mechanism to back its defence industry. There are few countries in the world capable of paying upfront, the majority - especially in the third world - require credit to get contracts moving. The SSM even said on numerous occasions that the lack of a credit mechanism is a big reason why competitors in Europe, Russia, China, etc, have been able to get ahead of Turkish companies.
If your defence industry begins securing multi-billion dollar exports with business activities spanning years or decades, then building that credit mechanism (while issuing loans) is doable. It'd be the same model used by Europe, China and the U.S. But securing business and actually getting buyers repay those terms is essential.
2. Regarding Pakistan. It is ultimately up to Turkey. If the Turkish Govt' determines that Pakistan cannot even pay the term, then Ankara has every right to not offer a sale. Simple. However, even if Pakistan is unable to offer a billion dollars up front, if it can do it over 5-7 years, then approving a sale - with credit - could be a good idea. If not Turkey, then that business will go to China.
3. Extending loans and credit also gives the Turkish side some added flexibility on the negotiating table. For example, you can offer a loan in-exchange for having Pakistan secure more subsystems from Turkey. For example, instead of Thales getting the CMS contract for the MILGEM, it'd be Aselsan.
For discussion's sake, imagine a ship deal is worth $1bn all inclusive - i.e. hulls, propulsion, electronics, etc.
If Pakistan had all the cash, then it might only award the Turkish economy $600m for the hulls and propulsion, but the $400m for electronics and weapons would go to Europe. However, if Turkey extends a $1bn loan, then its businesses will get all of the work, and the loan will be repaid in 10 annual installments (so it gets its money back plus the entire program instead of just 60% of it).
4. Pakistan can do installments. Yes, it can't manage too many programs at once, but two or so big-ticket programs are doable. Pakistan had managed the F-16 Block-52+ and Erieye purchases via installments, and it is now doing Chinese submarines via the same mechanism.