Try to keep a treat specially for cuddle time and use the same word/phrase when they are being picked up each time. Turn it into an event, a nice time, a treat time, with happy noises and chompy food. Try to pick up at around the same time every day at first, make it easy for them to expect the happy cuddle time. Only ever give that treat in the cuddle - that makes the cuddle special. Piggies respond to happy cuddles, loving cuddles, forming a real bond with you over time.
I've currently got Carmina (foster mum) and Chamomile (now three months old I think) in a cuddle together in between me and the laptop, between my arms, resting on the desk. To turn it into a precious time I am simply talking to them, kissing them on the head, stroking and basically paying them attention. This is enough, because Carmina is five now so she knows all about cuddles and what's expected. They just like the attention! However, although Carmina stays still to be picked up now (old hand) Chamomile has to be backed into a corner and held quite firmly (but very gently) and she isn't happy until she is with Carmina. So time and repeated cuddles will help!
Sarah