I think you can try image diagnosis  such as ultrasonographical or thermografical exams. US of cysticercus have been related in the literature. I'm not sure about thermography. Hope I have helped

I dont know a technique for recovery cysticercal cysts. For gastrointestinal nematodes, specifically for hypobiotic larvae recovery in abomasum of small ruminants, the abomasum artificial digestion is used. May you can use a similar technique to recovery cysticercal cysts. I just a suggestion. In this article appears the metodology, you can see.

Veterinary Parasitology 176 (2011) 201–207

Persistence of the efficacy of copper oxide wire particles against

Haemonchus contortus in sheep.

A.J. Galindo-Barboza, J.F.J. Torres-Acosta, R. Cámara-Sarmiento, C.A. Sandoval-Castro, A.J. Aguilar-Caballero, N.F. Ojeda-Robertos, R. Reyes-Ramírez, E. Espana-España

Other reference may be MAFF

Ministry of Agriculture Fisheries and Food (1986) Manual of veterinary parasitological laboratory techniques. Reference book 418. Her Majesty`s Stationery Office, London, UK.

Hi Laura, there is only references for cysticerci found in muscle tissue.

Am J Trop Med Hyg. 1990 Aug;43(2):194-9.

Prevalence and comparison of serologic assays, necropsy, and tongue examination for the diagnosis of porcine cysticercosis in Peru.

Gonzalez AE1, Cama V, Gilman RH, Tsang VC, Pilcher JB, Chavera A, Castro M, Montenegro T, Verastegui M, Miranda E, et al. 

You need to dissect all infected tissue and count total cysts, one by one.

Good luck!

Thanks to all. Unfortunately, cysticerci of T. pisiformis I'm looking for are in dead hares, in peritoneum and not in muscle. Fortunately they are easily visible without a microscope (at least when they are mature) but unfortunately sparse in the peritoneum and often attached one another so it should be quite difficult to count them with a standardized method.

i agree with Laura Stancampiano