How to apply
Taiwan has an online visa application system which lists Pakistan in the citizenship menu. They'll ask you where you want to apply for your visa, this means where you'll go for an interview (if applicable), present your documents and pick up your visa. They explain the process here.
Where to apply
The Taiwanese missions in Asia nearest to you are in India, but I'm assuming this might be problematic for you. There are others in the GCC countries (Dubai, Oman or Kuwait look closest to you), although as a Pakistani citizen you need a visa just to get to these places. None of these consulates have mention of any jurisdiction, so you could very possibly apply there.
As an alternative, Turkey (which also hosts a Taiwanese mission) might be a bit easier because they have an eVisa system.
Another alternative, as JonathanReez mentioned, is a visa agency in Pakistan that can represent you so you don't have to travel, however if Taiwan requests a physical presence (interview for example) they'll be of limited assistance.
As for the requirements of the visa, you'll find them all listed here or here. You'll need:
- A passport valid for at least six months;
- A duly completed application form with two photos taken within the past six months;
- An outbound airline ticket or verifiable proof of purchase of steamship ticket ;
- Documents verifying the purpose of visit;
- Other relevant documents.
- A visa fee of 50 or 100USD (single or multiple-entry)