On my bike (2002 DL1000), these are available -- look in the Speedometer fiche for "switch gum".
However, if something has deteriorated or eaten these rubber bits, you likely have far more serious problems. Mice also like to chew wiring, nest in airboxes, and generally be pains in the ass.
If they simply deteriorated, you might have an ozone problem in this area, and everything else made of rubber must be inspected or replaced.
2002 Suzuki DL1000 V-Strom, Dark Metallic Space Blue
1983 Suzuki GS850G, Cosmic Blue
2005 KLR685, Aztec Red - Turd II.2, the ReReTurdening