LiteSpeed does not have this setting.
One option is to consider striped backups.
You can do this trough the console and with the extended procedures.
With the console just click on add as many times as stripes you need(the screenshot is with backups on disk but it also works for TSM backups):
To do this with extended procedures please see an example below:
exec master.dbo.xp_backup_database
@database = 'Northwind'
, @tsmobject = 'fsMH\nw\stripetest01'
, @tsmobject = 'fsMH\nw\stripetest02'
, @tsmobject = 'fsMH\nw\stripetest03'
, @tsmobject = 'fsMH\nw\stripetest04'
, @tsmclientnode = '10.0.1.200'
, @tsmclientownerpwd = 'password'
, @tsmconfigfile = 'C:\Program Files\Tivoli\TSM\baclient\dsm.opt'
, @init = 1
