Yes, you can specify a custom separator up to 8 characters long. See the sample project below with the delimited text you provided split into 3 rows.
custom-delimiter.morph (1.9 KB)
Note that delimiter is removed once you split the text. So it has to be appended again, if necessary.
Alternatively, you can replace “;1;” with a common delimiter (e.g. pipe, “|”) using the replace() function, and then split the text using the pipe as delimiter.